5 Werkstofftechnik
Filtern
Dokumenttyp
- Vortrag (323)
- Posterpräsentation (94)
- Beitrag zu einem Tagungsband (55)
- Zeitschriftenartikel (52)
- Forschungsdatensatz (22)
- Buchkapitel (6)
- Dissertation (4)
- Sonstiges (3)
- Beitrag zu einem Sammelband (2)
- Corrigendum (1)
Sprache
- Englisch (563) (entfernen)
Referierte Publikation
- nein (563) (entfernen)
Schlagworte
- Additive Manufacturing (44)
- Corrosion (44)
- Additive manufacturing (38)
- Microstructure (24)
- Ontology (23)
- Glass (21)
- Creep (20)
- Fatigue (19)
- Transmission electron microscopy (17)
- Crack growth (16)
- CCS (14)
- Ceramics (14)
- Sintering (12)
- Degradation (11)
- 316L (10)
- Coarsening (10)
- EBSD (10)
- Alloy 2618A (9)
- CCUS (9)
- CO2 (9)
- Steel (9)
- Aluminium (8)
- Ceramic (8)
- Crystallization (8)
- Diffraction (8)
- Glass fiber reinforced polymers (8)
- High entropy alloys (8)
- Martensitic steel (8)
- Nanoparticles (8)
- Oxidation (8)
- Ti-6Al-4V (8)
- Anisotropy (7)
- Crystal plasticity (7)
- DCB (7)
- EN AW-2618A (7)
- FAIR (7)
- Fractography (7)
- Machine Learning (7)
- Mechanical testing (7)
- Scanning electron microscopy (7)
- Thermoelectrics (7)
- Water speciation (7)
- Aluminium alloy (6)
- CALPHAD (6)
- Geothermal (6)
- High temperature corrosion (6)
- High-temperature corrosion (6)
- Nickel-base superalloys (6)
- Powder (6)
- S-phase (6)
- Soda-lime silicate glass (6)
- Supercritical/dense phase CO2 (6)
- Vickers (6)
- Wind turbine blades (6)
- 3D printing (5)
- Aging (5)
- CCU (5)
- CO2 quality (5)
- Carbon steel (5)
- Carbon steels (5)
- Digitalization (5)
- Droplet corrosion (5)
- Electron microscopy (5)
- Fe-Al alloys (5)
- Hydrogen (5)
- Impurities (5)
- In situ (5)
- Intermetallics (5)
- Iron aluminides (5)
- LCF (5)
- Low Cycle Fatigue (5)
- Neutron diffraction (5)
- Non-destructive testing (5)
- PMD Core Ontology (5)
- Particle size (5)
- Polymer matrix composites (5)
- Residual stress (5)
- Semantic Web Technologies (5)
- Slurry (5)
- Sulfidation (5)
- Superaustenite steel (5)
- Thermomechanical fatigue (5)
- VSSA (5)
- Water content (5)
- X-ray diffraction (5)
- AGIL (4)
- Additive Fertigung (4)
- Alkali ions (4)
- Alkali zinc borate glasses (4)
- Alumina (4)
- Carbon capture (4)
- Composite (4)
- Creep behavior (4)
- Data Interoperability (4)
- Environmental stress cracking (4)
- FAIR data management (4)
- Fatigue crack growth (4)
- Heat treatment (4)
- High Cycle Fatigue (4)
- High alloyed steel (4)
- High entropy alloy (4)
- High temperature (4)
- In-space manufacturing (4)
- Inconel 686 (4)
- Knowledge Representation (4)
- Knowledge graph and ontologies (4)
- LTCC (4)
- Laser powder bed fusion (4)
- Mechanical properties (4)
- Microgravity (4)
- NTE (4)
- PE-HD (4)
- Pipeline (4)
- Pipeline network (4)
- Plattform MaterialDigital (4)
- Polyaniline (4)
- Reference data (4)
- Residual Stress (4)
- Sandwich (4)
- Scale-bridging (4)
- Scarf repairs (4)
- Selective laser melting (4)
- Semantic Interoperability (4)
- Shear modulus (4)
- TEM (4)
- Tensile test (4)
- Virtual experiments (4)
- Viscosity (4)
- Young's modulus (4)
- AISI 316L (3)
- Ab-initio (3)
- Advanced ceramics (3)
- Aluminium Alloy (3)
- Carbon capture storage (3)
- Carbon dioxide (3)
- Ceramic spring (3)
- Coating (3)
- Composites (3)
- Computed Tomography (3)
- Concrete (3)
- Corrosion Fatigue (3)
- Crack Propagation (3)
- Crack tip opening displacement (3)
- Creep data (3)
- Damage (3)
- Dark-field transmission electron microscopy (3)
- Dark-field transmission electron microscopy (DFTEM) (3)
- Dielectric strength (3)
- Diopside (3)
- Elastic modulus (3)
- FIB (3)
- Ferritic-martensitic steels (3)
- Foaming (3)
- Fracture Toughness (3)
- Fracture surface (3)
- Full Notch Creep Test (3)
- Full-Notch Creep Test (FNCT) (3)
- GD-OES (3)
- Glas (3)
- Gold nanoparticles (3)
- High temperature mechanical properties (3)
- High-density polyethylene (3)
- High-entropy alloys (3)
- Iron oxide nanoparticles (3)
- Layerwise Slurry Deposition (3)
- Layerwise slurry deposition (3)
- Lightweight materials (3)
- Lithium Ion Batteries (3)
- Mechanical behavior (3)
- Metadata schema (3)
- Microplastics (3)
- Microstructure Design (3)
- Modeling (3)
- Orientation (3)
- Oxide Glasses (3)
- P92 (3)
- Pitting (3)
- Polymer (3)
- Recommendations (3)
- Referenzdaten (3)
- Rotor blade (3)
- Roughness (3)
- SEM (3)
- SiO2 (3)
- Silicate Glasses (3)
- Simulation (3)
- Sol-gel (3)
- Solid-state (3)
- Solubility (3)
- Spectroscopy (3)
- Syngle Crystal alloy (3)
- TDEP (3)
- Temperature (3)
- Tempered Martensite Ferritic Steels (3)
- Tensile Test (3)
- Tensile data (3)
- Texture (3)
- Thermo-Mechanical Fatigue (3)
- Thermomechanics (3)
- Transmission electron microscopy (TEM) (3)
- Ultrasound (3)
- Utilization (3)
- Welding (3)
- Whole-chain CCS scenario (3)
- Wind turbine blade shells (3)
- μ-gravity (3)
- 3D-printing (2)
- AM (2)
- Adiabatic calorimeter (2)
- Agglomerates (2)
- Aggressive environment (2)
- Air-coupled ultrasonic testing (2)
- Airborne ultrasonic testing (2)
- Aluminum alloys (2)
- Analysis (2)
- Annealing (2)
- Aquifer (2)
- Automation (2)
- Binder Jetting (2)
- Bioactive glass (2)
- Biodiesel (2)
- Biofilm (2)
- Bond energy (2)
- Brinell hardness (2)
- CO2-storage (2)
- Calcium cobaltite (2)
- Capture (2)
- Carbon (2)
- Carbon Fiber Reinforced Plastics (2)
- Carbon storage (2)
- Casting (2)
- CeO2 (2)
- Cement (2)
- Ceria (2)
- Characterization (2)
- Chemically complex alloy (2)
- Chromium oxide (2)
- Coatings (2)
- Compositionally complex alloys (2)
- Condensation (2)
- Copper (2)
- Copper alloys (2)
- Corrosion fatigue (2)
- Crack evolution (2)
- Crack propagation (2)
- Crack propagation analysis (2)
- Creep-Fatigue (2)
- Creep-fatigue (2)
- Crevice corrosion (2)
- Cross linking (2)
- Crystal orientation (2)
- Cure process (2)
- Data Management (2)
- Data Structures (2)
- Data management (2)
- Data mapping (2)
- Dataset (2)
- Depth-profiling (2)
- Destabilization (2)
- Deuterium (2)
- Dielectric breakdown (2)
- Diesel (2)
- Diffraction Enhanced Imaging (2)
- Diffusion (2)
- Diffusion coefficient (2)
- Digital image correlation (2)
- Digital material representation (2)
- Digitization (2)
- Digtial Representation (2)
- Dislocation (2)
- Dispersion process (2)
- Distribution function (2)
- Dynamic mechanical analysis (DMA) (2)
- EDX (2)
- EDXRD (2)
- Electron beam induced modification (2)
- Electron-beam-induced modification (2)
- Environmental Stress Cracking (2)
- Environmental stress cracking (ESC) (2)
- FAIR data (2)
- Fatigue of sandwich shell structures (2)
- FeCr- alloys (2)
- Ferroelectret (2)
- Fiber reinforced polymer (2)
- Fracture Surface Analysis (2)
- Fracture surface analysis (2)
- Gitterkonstanten (2)
- Glass composition (2)
- Glass powder (2)
- Glass-ceramics (2)
- Grain boundary engineering (2)
- Hard machining (2)
- Hardness (2)
- High Alloyed Steel (2)
- High Entropy Alloy (2)
- High Temperature Corrosion (2)
- High Temperature Testing (2)
- High-entropy alloy (2)
- Hydrogen permeation (2)
- IN718 (2)
- IR (2)
- ISRU (2)
- Imaging techniques (2)
- In situ tensile test (2)
- In-situ (2)
- Infrastructure (2)
- Injection (2)
- Internal friction (2)
- Inverted classroom (2)
- Joined nickel-based alloys (2)
- Laminography (2)
- Laser Powder Bed Fusion (2)
- Laser ablation in liquid (2)
- Laser beam melting (2)
- Laser cladding (2)
- Lattice misfit (2)
- Layerwise (2)
- Lead borate glasses (2)
- Long-term behavior (2)
- Low cycle fatigue (2)
- Lunar habitat (2)
- Lunar regolith simulant (2)
- Manganese oxide (2)
- Material digital (2)
- Metal seal (2)
- Micromechanical model (2)
- Microstrucrue Design (2)
- Microstructural analysis (2)
- Microstructural characterization (2)
- Microstructure analysis (2)
- Microstructure evolution (2)
- Microstructure-property-correlation (2)
- Mikrostruktur (2)
- Mixed gas atmosphere (2)
- Monte-Carlo Simulation (2)
- Multilayer (2)
- Multilayer technology (2)
- NDT (2)
- NFDI (2)
- Nano powder (2)
- Nano-powder (2)
- Notches (2)
- Ontology development (2)
- Oxidation behavior (2)
- PMD (2)
- PMDco (2)
- Paving (2)
- Phase change material (2)
- Phasenidentifikation (2)
- Photon counting detector (2)
- Polyethylene, PE-HD (2)
- Porosity (2)
- Precipitation (2)
- Process monitoring (2)
- Protective coating (2)
- Push-out Test (2)
- Reaction sintering (2)
- Reference material (2)
- Residual Stresses (2)
- Residual stresses (2)
- Ressidual stress (2)
- Round Robin (2)
- S355 steel sheet (2)
- SAXS (2)
- SIMS (2)
- SLM (2)
- Salt eutectics (2)
- Sample preparation (2)
- Selective Laser Melting (2)
- Semantic Representation (2)
- Sibayak (2)
- Silicon Carbide (2)
- Silver diffusion (2)
- Silver nanoparticle (2)
- Silver-glass-metallization-paste (2)
- Sintering additives (2)
- Sol-gel coating (2)
- Solar sintering (2)
- Spray drying (2)
- Spring constant (2)
- Standard (2)
- Standardization (2)
- Starch (2)
- Starch nanoparticle (2)
- Storage (2)
- Stress relaxation (2)
- Sulfiding (2)
- Superalloy (2)
- Supercritical CO2 (2)
- Surface (2)
- Surface Energy (2)
- Surface crystallization (2)
- Surface energy (2)
- Synchrotron Tomography (2)
- Synthetic air (2)
- TED-GC-MS (2)
- Tensile Properties (2)
- Tensile testing (2)
- Thermal Spray (2)
- Thermal energy storage (2)
- Thermoelectric (2)
- Thermogravimetry (2)
- Thermoset polymers (2)
- Titanium (2)
- Titanium oxide (2)
- ToF-SIMS (2)
- Topography (2)
- Transparent ceramics (2)
- Two Photon Polymerization (2)
- UV-irradiation (2)
- Viscoplasticity (2)
- Wall thickness (2)
- Weibull Distribution (2)
- Wind energy (2)
- Wind turbine (2)
- Wood protection (2)
- X-Ray Diffraction (2)
- X-ray laminography (2)
- X-ray refraction (2)
- XANES (2)
- XRD (2)
- Zero-g (2)
- corrosion (2)
- µ-gravity (2)
- 150 Years (1)
- 2PP (1)
- 3D (1)
- 3D Reconstruction (1)
- 3D glass structure model (1)
- 3D imaging (1)
- 3D materialography (1)
- 5G (1)
- 9-12% Cr ferritic-martensitic steels (1)
- AFM (1)
- AISI 304L (1)
- ATZ (1)
- Accelerated integration scheme (1)
- Acid-leaching (1)
- Acids (1)
- Active thermography (1)
- Adiabatic shear bands (1)
- Adolf Martens (1)
- Advanced manufacturing (1)
- Advanced wastewater treatment (1)
- Aerospace (1)
- Ageing (1)
- Aggressive environement (1)
- Aggressive gases (1)
- Aging mechanisms (1)
- Al-Cu-Li alloys (1)
- Al-Li alloys (1)
- Al2CuMg (1)
- Al2O3 (1)
- Alkali zinc borate glass (1)
- Alkali-activated materials (1)
- Alloy 2818A (1)
- Alpha-tricalcium phosphate (1)
- Alumina toughened zirconia (1)
- Aluminosilicate glasses (1)
- Aluminum (1)
- Aluminum alloy (1)
- Amorphous silica (1)
- Analytical services (1)
- Anhydrite (1)
- Artefact (1)
- Atacama Desert (1)
- Atmospheric Plasma Spraying (1)
- Atmospheric plasma spraying (1)
- Atomic packing factor (1)
- Atomization (1)
- Austenitic cast iron (1)
- Austenitic stainless steel (1)
- Austenitic steel (1)
- Austenitic steel 316L (1)
- Austenitischer Stahl (1)
- Automated finite element analysis (1)
- Automatische Finite Element Simulation (1)
- BTS (1)
- Biaxial strength (1)
- Bio Ceramics (1)
- Bio-ceramic engineering (1)
- Bioactive Glass (1)
- Bioceramics (1)
- Bioresorbable (1)
- Blended learning (1)
- Blähen (1)
- Borate glasses (1)
- Breakdown strength (1)
- Brittle / ductile fracture behavior (1)
- Brittle fracture (1)
- Brown-rot fungi (1)
- Burst test (1)
- CALPHAD databases analysis (1)
- CLS (1)
- CO2 Corrosion (1)
- CO2-corrosion (1)
- Cabon capture and storage (1)
- Calcination (1)
- Calcium manganate (1)
- Calcium sulfates (1)
- Calibration (1)
- Cantor alloy (1)
- Carbidic austempered ductile iron (1)
- Carbon steels (1)
- Carbon Capture (1)
- Carbon Capture, Utilization and Storage (CCUS) (1)
- Carbon Fibers (1)
- Carbon capture and storage (1)
- Carbon fibre-reinforced-plastics (1)
- Catalogue of services (1)
- Ccs (1)
- Centrifugal casting (1)
- Ceramic multilayer (1)
- Ceramic nano particles (1)
- Ceramic springs (1)
- Ceramics 3D printing (1)
- Certification Standard 22 (1)
- Certified Referencematerial (1)
- Charpy test (1)
- Chemically Complex Alloy (1)
- Chemically complex alloys (1)
- Chemo-mechanical coupling (1)
- Chromatography (1)
- Chromia (1)
- Co-axial monitoring (1)
- Co-firing (1)
- Co-segregation (1)
- Co2-Storage (1)
- Complex borides (1)
- Complex concentrated alloy (CCA) (1)
- Complex loading (1)
- Component assessment (1)
- Composite pressure vessels (1)
- Composite structures (1)
- Composite testing (1)
- Computed tomography (1)
- Coniophora puteana (1)
- Contamination (1)
- Continnum damage model (1)
- Cooling simulations (1)
- Corrosion and storage (CCUS) technology (1)
- Corrosion mechanism (1)
- Corrosion resistance (1)
- Coulomb explosion (1)
- Cow stress (1)
- Cr2O3 (1)
- CrMnFeCoNi (1)
- Crack healing (1)
- Creep anisotropy (1)
- Creep behaviour (1)
- Creep, Creep Rupture, and Stress Rupture (1)
- Critical energy release rate (1)
- Crop protection formulations (1)
- Crystal Defects (1)
- Crystal Orientation (1)
- Crystal Plasticity Modelling (1)
- Crystal lattice (1)
- Cubical Iron Oxide (1)
- Cubical shape (1)
- Cycle jump (1)
- Cyclic R-Curve (1)
- Cyclic loading (1)
- Cyclic oxidation (1)
- Cyclic softening (1)
- Cytocompatibility (1)
- DED-L (1)
- DLS (1)
- Damage Behavior (1)
- Damage Tolerance (1)
- Damage evolution (1)
- Damage mechanisms (1)
- Data Exchange (1)
- Data Fusion (1)
- Data Mapping (1)
- Data analysis (1)
- Data format (1)
- Data fusion (1)
- Data linking (1)
- Data space (1)
- Data storage (1)
- Data structure (1)
- Deep learning (1)
- Defect detection (1)
- Defects (1)
- Defects phase diagram (1)
- Defects thermodynamics (1)
- Deformation behavior (1)
- Dense phase (1)
- Density (1)
- Density-based Model (1)
- Density-based Thermodynamics (1)
- Density-based model (1)
- Density-based phase-field modelling (1)
- Dental (1)
- Dentine (1)
- Die casting (1)
- Dielectric Spectroscopy (1)
- Dielectric breakdown strength (1)
- Dielectric characterization (1)
- Dielectric properties (1)
- Diffraction Elastic Constants (1)
- Diffraction contrast (1)
- Diffusivity (1)
- Digital representation (1)
- Dislocation substructure (1)
- Dislocations (1)
- Disordered assemblies (1)
- Dissimilar metal weld (1)
- Dissolved water (1)
- Distributed fiber optic sensors (1)
- Distributed fibre optic sensors (1)
- Diversity (1)
- Driving physical mechanism (1)
- Droplet (1)
- Dual-energy (1)
- Ductile iron (1)
- Dwell-Fatigue (1)
- Dynamic mechanical analysis (1)
- Dynamisch Mechanische Analyse (1)
- EAC-1A (1)
- EASA (1)
- EC4SafeNano (1)
- EIS (1)
- EN AW 2618A a (1)
- Early oxidation (1)
- Elastic constants (1)
- Elastic microstructure (1)
- Elasticity (1)
- Electric field distribution (1)
- Electric field strength (1)
- Electrical insulation (1)
- Electrochemical deposition (1)
- Electrochemical dressing (1)
- Electromicroscopy (1)
- Electron Backscatter Diffraction (1)
- Electron Microscopy (1)
- Electron backscatter diffraction (1)
- Electron backscattered diffraction (EBSD) (1)
- Electron beam-induced fragmentation (1)
- Electron diffraction (1)
- Electron energy (1)
- Electronic Lab Notebook (1)
- Electropolishing (1)
- Enamel (1)
- Endurance Limit (1)
- Energy distribution (1)
- Environmental Stress Cracking (ESC) (1)
- Environmentally assisted cracking (1)
- Epoxy (1)
- Etching (1)
- European Centre (1)
- FAIR Data (1)
- FAIR Data Management (1)
- FCH JU (1)
- FNCT (1)
- Fabrication method (1)
- Failure test (1)
- Fatigue Crack Growth (1)
- Fatigue Life Evaluation (1)
- Fatigue crack propagation (1)
- Fatigue damage (1)
- Fatigue fracture (1)
- Fatigue of sandwich structures (1)
- Fatigue performance (1)
- Feldspar (1)
- Fem (1)
- Ferritic Alloys (1)
- Fiber (1)
- Fiber reinforced polymers (1)
- Film depositition (1)
- Fine Powder (1)
- Finite element analysis (1)
- Finite elmenet simulation (1)
- Finite-Elemente-Methode (1)
- First year students (1)
- Flipped classroom (1)
- Flow Coefficient (1)
- Flowability (1)
- Fluorescence spectroscopy (1)
- Fluoride nanoparticles (1)
- Fluorolytic sol−gel (1)
- Focussed ion beam growth (1)
- Force-distance diagram (1)
- Fourier transform infrared spectroscopy (1)
- Fracture (1)
- Fracture Mechanics (1)
- Fracture behavior (1)
- Fracture mechanics (1)
- Fracture surface energy (1)
- Fracture toughness (1)
- Fragility (1)
- Freeze Drying (1)
- Fresnoit (1)
- Full Notch Creep Test (FNCT) (1)
- Full-Notch Creep Test (1)
- Full-notch creep test (1)
- Fungi (1)
- GFRP (1)
- Gas flow assisted powder deposition (1)
- Gas storage (1)
- Gasabgabe (1)
- Gasgehalt (1)
- Gefüge (Werkstoffkunde) (1)
- General Chemistry (1)
- Geometrical factors (1)
- Geopolymers (1)
- Glass Fibres (1)
- Glass ceramic (1)
- Glass fiber reinforced polymer (1)
- Glass fibre reinforced plastics (1)
- Glass forming (1)
- Glass liner (1)
- Glass matrix composite (1)
- Glass melt (1)
- Glass melting (1)
- Glass screening device (1)
- Glass structure (1)
- Glass transformation temperature (1)
- Glass-ceramic (1)
- Gold nanoparticle synthesis (1)
- Gradient-enhanced damage (1)
- Grain boundaries (1)
- Granules (1)
- Graphic design (1)
- Gypsum (1)
- HEA (1)
- HV-Insulation (1)
- Hardness test (1)
- Heat Treatment (1)
- Heat Treatments (1)
- Heißgasextraktion (1)
- High - temperature corrosion (1)
- High Entropy Alloys (1)
- High Voltage Insulation (1)
- High alloyed steels (1)
- High cycle fatigue (1)
- High entropy superalloys (1)
- High-Temperature Corrosion (1)
- High-density polyethylene (PE-HD) (1)
- Hochentropie-Legierung (1)
- Hochentropielegierung (1)
- Honing (1)
- Honing Stone (1)
- Horizon 2020 (1)
- Hot Press (1)
- Hot isostatic pressing (1)
- Hot isostatic pressing (HIP) (1)
- Hot pressing (1)
- Hot stage microscopy (1)
- Hybrid Manufacturing (1)
- Hydrogen permeability (1)
- Hydrogen sensor (1)
- Hydrogen sensors (1)
- Hydrogen storage tank (1)
- Hyper-arid (1)
- IN738LC (1)
- IR spectroscopy (1)
- Imaging (1)
- Implant failures (1)
- Implants (1)
- In-Situ Testing (1)
- In-situ tomography (1)
- In718 (1)
- Inconel 625 (1)
- Inconel 686 coating (1)
- Inconel 718 (1)
- Indentation hardness (1)
- Initial attachment (1)
- Interface (1)
- Interface Strength (1)
- Interfacial Spinodal (1)
- Interfacial shear strength (1)
- Interoperability (1)
- Inverse ostwald ripening (1)
- Investment casting (1)
- Ionic porosity (1)
- Iron oxide (1)
- Irregular topography (1)
- Kikuchi diffraction (1)
- Kikuchi pattern (1)
- Knowledge Graph (1)
- Knowledge Graphs (1)
- Knowledge graph (1)
- Kriechen (1)
- Kristallisation (1)
- L-PBF (1)
- LMD (1)
- LTCC multilayer (1)
- Laser (1)
- Laser Beam Melting (1)
- Laser Cladding (1)
- Laser Powder Bed fusion (1)
- Laser Scanning Microscopy (1)
- Laser Scanning Microscopy (LSM) (1)
- Laser curing (1)
- Laser induced slipcasting (1)
- Laser light scattering (1)
- Laser-induced slip casting (1)
- Lattices (1)
- Layer depostion (1)
- Lecture films (1)
- Lecture videos (1)
- Legierung mit komplexer Zusammensetzung (1)
- Li-ion battery (1)
- Life cycle (1)
- Lifetime prediction (1)
- Lightweighting (1)
- Limestone Filler (1)
- Lithium-ion batteries (1)
- Lithography-based technologies (1)
- Local landscape evolution (1)
- Localized plasmons (1)
- Long-term storage (1)
- Lorenz transmission electron microscopy (1)
- Low Cycle Fatigue (LCF) (1)
- Low-Cycle-Fatigue (1)
- Low-cycle fatigue. (1)
- Low-cycle-fatigue behaviour (1)
- MEA (1)
- MOUSE (1)
- Manufacturing (1)
- Martensitic steel (1)
- Mass transport (1)
- Mat-o-lab (1)
- Material Digital (1)
- Material characterization (1)
- Material defects (1)
- Material degradation (1)
- Material oxidation (1)
- MaterialDigital (1)
- Materials Chemistry (1)
- Materials Modelling (1)
- Materials Science (1)
- Materials science (1)
- Materials testing (1)
- Mechanical Behavior (1)
- Mechanical Engineering (1)
- Mechanical and thermal testing (1)
- Mechanics of Materials (1)
- Mechanistic Modelling (1)
- Medium Entropy Alloys (1)
- Medium entopy alloy (1)
- Medium-entropy alloy (1)
- Mehrskalenmodell (1)
- Melt pool boundary (1)
- Metal powder characterization (1)
- Metallic components (1)
- Metallic glasses (1)
- Metallic silver precipitates (1)
- Metallography (1)
- Metals and Alloys (1)
- Metformin (1)
- Metrology (1)
- Micro computed tomography (1)
- Micro-shrinkages (1)
- Microbiologically influenced corrosion (1)
- Microhardness (1)
- Micromanipulation (1)
- Microsegregation (1)
- Microstructural evolution (1)
- Microstructural orientation (1)
- Microstructure Characterization (1)
- Microstructure Evolution (1)
- Microstructure characterisation (1)
- Microstructure design (1)
- Microstructure modification (1)
- Mid-Level Ontology for MSE (1)
- Mikroplastik (1)
- Missing acknowledgment (1)
- Mixed Ca-K-Na phosphates (1)
- Mn3O4 (1)
- Molecular Dynamics (1)
- Molecular dynamics (1)
- Monte-Carlo-Analysis (1)
- Mortar (1)
- Mortel (1)
- Multi-principal element alloys (1)
- Multilayertechnik (1)
- NFDI-MatWerk (1)
- NMR (1)
- Na and K rhenanites (1)
- Nano CRM (1)
- Nano metal fluorides (1)
- Nano particle (1)
- Nano screening (1)
- Nano-assemblies (1)
- Nano-ceramic-additive-manufacturing photoresin (1)
- Nano-landscape (1)
- Nano-powder characterization (1)
- Nano-safety (1)
- NanoCAM (1)
- Nanoindentation (1)
- Nanomaterial screening (1)
- Nanomaterials (1)
- Nanoparticle synthesis (1)
- Nanoplattform (1)
- Nanostructure (1)
- Nanostructure quantification (1)
- Negative charged microparticle (1)
- Net zero (1)
- Networking (1)
- Neutron Diffraction (1)
- New standards (1)
- Ni-Resist (1)
- Nickel based coatings (1)
- Nickel-base alloy (1)
- Nickel-base superalloy (1)
- Nimonic 75 (1)
- Niobium alloying (1)
- Non-desired foaming (1)
- Nondestructive testing (1)
- Normung (1)
- Nucleation (1)
- Nucleation mode (1)
- Nucleation tendency (1)
- Online quality control (1)
- Online teaching (1)
- Ooxidation (1)
- Optic (1)
- Optical backscatter reflectometry (1)
- Optical criterion (1)
- Optical fibre (1)
- Orientation-dependent microstructure (1)
- Oriented surface crystallization (1)
- Oxide glass (1)
- Oxide scale (1)
- Oxides (1)
- Oxidglas (1)
- P92 steels (1)
- PA6.6 (1)
- PBF-LB/M/316L (1)
- PPA (1)
- Particle Size Distribution (1)
- Particle morphology (1)
- Pattern matching (1)
- Permeability (1)
- Phase Diagrams (1)
- Phase Separation (1)
- Phase analysis (1)
- Phase diagram (1)
- Phase field simulation (1)
- Phase separation (1)
- Phase transformation (1)
- Phase transformations (1)
- Phase-Field Simulation (1)
- Phase-Field Simulations (1)
- Phase-field (1)
- Phase-field Simulation (1)
- Phase-field simulation (1)
- Photocatalysis (1)
- Physical properties (1)
- Physically based material model (1)
- Physics-informed Neural Network (1)
- Phytolith (1)
- Pipelines (1)
- Planetary surface (1)
- Plasticity (1)
- Platform Material Digital (1)
- Platform Material Digital (PMD) (1)
- Platform MaterialDigital (1)
- Platform MaterialDigital (PMD) (1)
- Pole figures (1)
- Polyethylen (1)
- Polyethylene (1)
- Polymer Matrix Composite (1)
- Polymer Matrix Composites (1)
- Polymer-Ceramic-Composite (1)
- Polymer-ceramic mixtures (1)
- Porcelain (1)
- Pores (1)
- Portfolio (1)
- Powder bed density (1)
- Powder deposition (1)
- Powder-based processes (1)
- Powdered activated carbon (1)
- Power plant (1)
- Precipitation Analysis (1)
- Precipitation hardening (1)
- Preparation (1)
- Pressure assisted sintering (1)
- Pressure-assisted sintering (1)
- Process (1)
- Process Monitoring (1)
- Proficiency test (1)
- Property simulation (1)
- Pull-out composite materials (1)
- Quality assurance (1)
- Quantitative Precipitation Analysis (1)
- Radii distribution (1)
- Rafting (1)
- Raman spectroscopy (1)
- Recycling (1)
- Reference Data (1)
- Reference Dataset (1)
- Reference Material (1)
- Reference material BCR-425 (1)
- Reference nanomaterials (1)
- Reference nanoparticles (1)
- Refractory chemically complex alloy (1)
- Refractory chemically complex alloys (1)
- Refractory high entropy alloys (1)
- Relaxation (1)
- Relaxation metallic glasses (1)
- Relaxation tests (1)
- Relaxationsphänomene (1)
- Reliable characterization (1)
- Repair of sandwich shell structures (1)
- Repair patch (1)
- Reproducibility (1)
- Research Data Management (1)
- Residual stress analysis (1)
- Resistance (1)
- Resistance stress (1)
- Review (1)
- Rheology (1)
- Rhodonia placenta (1)
- Rissausbreitung (1)
- Risswachstum (1)
- Robot-assisted galss melting (1)
- Roboter (1)
- Robotische Glasschmelzanlage (1)
- SEM wood characterization (1)
- SHM (1)
- Safety assessment (1)
- Sailplane Development Panel (1)
- Sall-angle scattering (1)
- Salt melt (1)
- Sandwich structures (1)
- Scaffold (1)
- Scanning Electron Microscopy (SEM) (1)
- Scanning electron microscope (1)
- Scanning electron microscopy (SEM) (1)
- Scanning transmission electron microscopy (STEM) (1)
- Scarf joint repair (1)
- Scarf joint repairs (1)
- SchwarzP cells (1)
- Screen printing (1)
- Screening method (1)
- Segregation Engineering (1)
- Self-healing (1)
- Semantic Interioerability (1)
- Semantic Web (1)
- Semantic Web technologies (1)
- Semantic web (1)
- Sensor (1)
- Sewage treatment plant (1)
- Silicatglas (1)
- Silver (1)
- Silver cluster (1)
- Silver glass paste (1)
- Silver metallization paste (1)
- Silver precipitates (1)
- Silver-glass metallization paste (1)
- Simulation of concrete (1)
- Single crystal superalloys (1)
- Single-Crystal (1)
- Single-crystals (1)
- Sinter additive (1)
- Sinter retardation (1)
- Sintering atmosphere (1)
- Sintern (1)
- Size (1)
- Size and size distribution (1)
- Size distribution (1)
- Sliding simulation (1)
- Slip-rolling (1)
- Slow crack growth (1)
- Slow crack growth (SCG) (1)
- Small angle x-ray scattering (1)
- Small-Angle X-ray Scattering (1)
- Small-angle Scattering (1)
- Soda-lime-silica glass (1)
- Sodium zinc borate glass (1)
- Sodiumborosilicate glasses (1)
- Soil sample (1)
- Solid solution strengthening (1)
- Solidification (1)
- Space (1)
- Space exploration (1)
- Spark plasma sintering (1)
- Spinodal Decomposition (1)
- Split Hopkinson bar (1)
- Spring constant (1)
- Stainless steel (1)
- Steels (1)
- Strain rate dependence (1)
- Strength (1)
- Structural health monitoring (SHM) (1)
- Structure (1)
- Structured Data (1)
- Structured heating (1)
- Subsurface defects (1)
- Superalloys (1)
- Superaustenite steel (1)
- Supercritical/dense phase CO 2 (1)
- Superlegierung (1)
- Surface Nucleation (1)
- Surface roughness (1)
- Surface-induced Melting (1)
- Swept wavelength interferometry (SWI) (1)
- Synchrotron CT (1)
- Synchrotron radiation (1)
- Synchrotron tomography (1)
- TAHYA (1)
- TED (1)
- TMF (1)
- TMF experiments (1)
- Technical Ceramics (1)
- Temperature driven process (1)
- Tempered martensite ferritic steel (1)
- Tempered martensite ferritic steels (1)
- Tempered martensite-ferritic steel (1)
- Tensile Test Ontology (1)
- Tensile stress relaxation (1)
- Termites (1)
- Test Improvement (1)
- Texturation (1)
- Thermal degradation (1)
- Thermal stress (1)
- Thermo mechanical fatigue (1)
- Thermo-mechanical fatigue (1)
- Thermo-mechanical-loading (1)
- Thermo-mechanics (1)
- Thermo-optical measurement (1)
- Thermoanalysis (1)
- Thermoanalytical Methods (1)
- Thermodynamic analysis (1)
- Thermodynamic stability (1)
- Thermodynamische Stabilität (1)
- Thermoelectric generator (1)
- Thermoelectric generator design (1)
- Thermoelectric oxide (1)
- Thermoelectric oxides (1)
- Thermogravimetric analysis (1)
- Thermomechanical Fatigue (TMF) (1)
- Thermomechanische Ermüdung (1)
- Thermoplastic (1)
- Thesaurus (1)
- Thin tribofilm (1)
- Tomography (1)
- Tools (1)
- Tooth wear (1)
- Transducers (1)
- Transmission electron microscope (TEM) (1)
- Two-photon adsorption (1)
- Two-photon polymerization (1)
- Under cyclic loading (1)
- Utilization, and storage (CCUS) technology (1)
- VCSEL (1)
- VM12 SHC (1)
- Vacancies (1)
- Vacuum hot extraction (1)
- Very high cycle fatigue (1)
- Vickers Hardness (1)
- Vickers hardness (1)
- Vickers indentation (1)
- Viscous sintering (1)
- Volume Fraction (1)
- Volume specific surface area (1)
- Wasser (1)
- Waste water (1)
- Weibull distribution (1)
- Welding processing influences (1)
- Wet dispersion (1)
- Wind turbine blade shell structures (1)
- Withstand voltage tests (1)
- Workshop (1)
- X-ray imaging (1)
- X-ray refractography (1)
- X-ray scattering (1)
- Young´s Modulus (1)
- Young’s Modulus (1)
- alumina (1)
- arbon capture (1)
- bioactive (1)
- biomaterials (1)
- bone (1)
- carbon steel (1)
- ceramic (1)
- ceramics (1)
- condensate (1)
- dental (1)
- electrochemical characterization (1)
- high entropy alloys (1)
- hydrogen storage (1)
- impurities (1)
- laser cladding (1)
- microstructure analysis (1)
- multi scale testing (1)
- oxidation (1)
- pitting corrosion (1)
- scanning electron microscopy (1)
- selective laser melting (1)
- sulfidation (1)
- utilization, and storage (CCUS) technology (1)
- volume resistivity (1)
Organisationseinheit der BAM
- 5 Werkstofftechnik (563)
- 5.1 Mikrostruktur Design und Degradation (169)
- 5.2 Metallische Hochtemperaturwerkstoffe (143)
- 5.4 Multimateriale Fertigungsprozesse (115)
- 5.6 Glas (68)
- 5.3 Polymere Verbundwerkstoffe (63)
- 5.5 Materialmodellierung (57)
- 7 Bauwerkssicherheit (52)
- 8 Zerstörungsfreie Prüfung (46)
- 9 Komponentensicherheit (41)
The chemically complex alloys (CCAs) that contain mostly refractory elements (rCCAs), may be highly resistant to heat and load, which makes them attractive candidates for use at extremely high temperatures associated with many technological applications, e.g. aeroengine turbines. However, the field of CCAs, especially their resistance in harsh (oxidative) and hot environment is still young and not much experimental evidence for the understanding mechanisms in this regime is available, which the proposed study addresses. For safe use in structural applications, in addition to their mechanical performance, the environmental resistance of this alloy is also critical. Surface degradation can significantly decrease the mechanical resistance during high temperature exposure, leading to premature failure. The AlMo0.5NbTa0.5TiZr rCCA only contains Al as a protection candidate and it is composed of a coherent B2/bcc nanoscopic cube-on-cube interweave and an hexagonal phase. The evaluation of the oxidation process in the AlMo0.5NbTa0.5TiZr rCCA in the heat-treated state has not been assessed yet. The proposed study focusses on a deeper understanding of the formation mechanism and growth kinetics of oxides at high temperature in the AlMo0.5NbTa0.5TiZr rCCA using synchrotron radiation. Due to the envisaged high temperature structural applications, the alloy is evaluated in an oxidation environment specifically between 800°C and 1000°C.
The development of refractory CCAs has been explored for potential use in high temperature applications. An example of this is the AlMo0.5NbTa0.5TiZr alloy, which resembles the well-known γ/γ’ microstructure in Ni-Base superalloys with cuboidal particles embedded in a continuous matrix. The aim of this work is to evaluate the alloy’s mechanical behavior under tension in the temperature range 800-1000°C, by applying creep tests under vacuum (excluding oxidation effects). Some little temperature influence on minimum creep rate @ 1000 and 1100 °C was found and at a first glance, and Norton plots shows that deformation is probably both diffusion and dislocation controlled. However, further work is needed to stablish deformation and degradation micro mechanisms in the studied creep regime.
Microstructural characterization of the AlMo 0.5 NbTa 0.5 ZrTi refractory complex concentrated alloy
(2020)
A set of some unexpected and interesting microstructures has put the so-called complex concentrated alloys (CCAs) in the eye of the scientific community and the AlMo0.5NbTa0.5TiZr refractory (r)CCA, aimed at substituting Ni-base superalloys in gas turbine applications, belongs to this alloy family. The AlMo0.5NbTa0.5TiZr rCCA was studied by SEM, EDX, EBSD and TEM, showing the presence of a nanoscopic basket-wave structure inside the grains, with two BCC phases. Additionally, thermodynamic calculations on the AlMo0.5NbTa0.5TiZr alloy were done with two different proprietary databases that anticipate two BCC-disordered phases with distinct constitutions as well as an HCP phase.
This contribution contains the raw data used to compare experimental results with thermodynamic calculations using the CALPHAD method, which is related to the research article “The AlMo0.5NbTa0.5TiZr refractory high entropy superalloy: experimental findings and comparison with calculations using the CALPHAD method” [1] , and therefore this article can be used as a basis for interpreting the data contained therein. The AlMo0.5NbTa0.5TiZr refractory superalloy was characterized in the cast and annealed condition (1400 °C for 24 h) in order to measure grain size and to identify and measure the size and area fraction of the phases present. The raw data of this article include X-ray diffraction (XRD) measurements, microstructural characterization by scanning and transmission electron microscopy (SEM and TEM), and elemental analysis by energy dispersive X-ray spectroscopy (EDX). XRD includes the determination of phases and the lattice parameters (A2, B2, and hexagonal structure). Microstructural analysis by scanning and transmission electron microscopy includes (1) identification of composition, size, and volume fraction of the present phases and (2) determination of grain size. Based on these experimental data, it is possible to identify similarities and discrepancies with the data calculated using the CALPHAD method for the alloy under study in Ref. [1] , which provides the basis for better and more efficient development of reliable databases.
Today’s industrial demands challenge the research and development sector to make advances in the design and properties of materials that can withstand harsh environments. The AlMo0.5NbTa0.5TiZr refractory high-entropy superalloy (RSA), with a remarkable morphological similarity to the γ/γ' microstructure of Ni-based superalloys and promising high-temperature compressive properties, has been considered as a candidate for structural applications. However, additional properties need to be investigated in order to assess the suitability of this alloy for high temperature applications. Therefore, this work investigates the thermodynamic and microstructural stabilities of the RSA at room temperature and between 900 and 1100 °C, and their influence on the mechanical properties. Although it is possible to improve the mechanical properties at 20 °C by tuning the cooling rate, long-term high temperature exposures lead to phase instabilities that negatively influence the creep behavior.
High-temperature corrosion is a widespread problem in various industries.
As soon as a hot and reactive gas (CO2, O2, H2O, SO2, NOx, etc.) is in contact with a solid, physico-chemical processes at the surface and interfaces lead to material degradation. The processes are dynamic and controlled by thermodynamic and kinetic boundary conditions. Whether a reaction product is protective or not depends on various factors, such as chemical composition of the solid and the reactive media, surface treatment as well as diffusion and transport paths of cations and anions. Resulting chemical and structural inhomogeneities with the corrosion layers are characterized by off stoichiometry within cationic and anionic sub lattices. The competitive processes can be studied by various techniques of applied crystallography.
This chapter gives an overview on the challenges of chemical-structural Analysis of reaction products by crystallographic methods such as X-ray diffraction and X-ray near-edge structure spectroscopy and scanning electron microscopy electron backscatter diffraction (SEM-EBSD) for corrosion science.
Corrosion Science Meets X-Rays, Neutrons and Electrons. The presentation gives an overview on current research activities applying in-situ X-ray diffraction and spectroscopy for a better understanding of fundamental mechanisms of high temperature corrosion. Additionally the knowledge gain by applying neutron powder diffraction and EBSD analysis is presented.
A variety of materials of technological interest change their properties through contact with reactive media. Solid-gas reactions lead to a variety of reaction products on the surfaces and internal interfaces. The observation of nucleation and growth processes in the environment where they occur (in situ) from a chemical-structural perspective is especially challenging for aggressive atmospheres. The talk presents innovative approaches to study corrosion mechanisms using advanced X-ray methods. Using energy dispersive X-ray diffraction and X-ray absorption spectroscopy in different tailor made environmental reaction chambers, valuable insights into high temperature oxidation and sulfidation processes were gained. Fe-based alloys were exposed to hot and reactive atmospheres containing gases like SO2, H2O and O2 at 650°C. During the gas exposure the tailor made reaction chambers were connected to a high energy diffraction end station at the synchrotron. The crystallization and growth of oxide and sulfide reaction products at the alloy surfaces were monitored by collecting full diffraction pattern every minute. Careful examination of shape and intensity of phase-specific reflections enabled to a detailed view on growth kinetics. These studies showed, oxides are the first phases occurring immediately after experimental start. As soon as reactive gas media enter the chamber, the conditions change and different reaction products, such as sulfides start to grow. A comparison of different gas environments applied, illustrated the differences in the type of reaction products. The in situ observation of high temperature material degradation by corrosion made it possible to study the contribution of phases, which are not stable at room temperature. For instance, wuestite (Fe1-xO), was frequently observed at high temperatures in humid gases on Fe with 2 wt.% and 9 wt.% chromium, but not at room temperature. The strength of the occurrence of this phase additionally explains why, despite a higher Cr content, ferritic alloys with 9 wt.% Cr in a challenging atmosphere prevent the intrinsic formation of protective layers. The in situ observations were supplemented by careful considerations of thermodynamic boundary conditions and detailed post characterization by classical metallographic analysis. Additionally, the structure and chemistry of the dominant oxide layers were evaluated using X-ray absorption near edge structure spectroscopy. The talk will give an overview about chances and challenges for studying high temperature corrosion phenomena by advanced X-ray methods.
Ferritic-austenitic chromia-forming alloys are frequently used as boiler tubes and heat exchanger materials for fossil-,biomass, and co-fired power plants. In all applied environments several strongly corrosive gaseous species such as CO2, SO2, SO3, H2O, O2 exist, causing materials degradation by high-temperature corrosion. The elucidation of degradation mechanisms introduced by multiple gases is challenging due to the presence of different oxidizing agents contributing to the competing reactions for oxidation, sulfurization or carburization. The degradation processes can be divided into initial stages, a transitional stage and the further proceeding steady-state oxidation reaction. Especially the long-term steady-state oxidation and further materials’ life-time are strongly dependent on the initial stages. The adsorption and absorption of the reactive species at the alloy surface and the growing oxide in the initial reaction is further influenced by dissociation and re-reactions of the gas phase molecules. To understand these mechanisms from a fundamental point of view in more detail, dedicated experiments and advanced characterization techniques on various length scale need to be applied. Real-time approaches using highly energetic synchrotron X-ray diffraction showed a high potential to enlighten competitively mechanisms by following the corrosion reactions in-situ in the environment they occur. Despite various other thin film characterization techniques, time of flight secondary ion mass spectroscopy (ToF-SIMS) is a powerful tool to visualize light atoms or labeled isotopes enabling the Differentiation between different oxidizing species. It was especially shown to be applicable in challenging atmospheres containing KCl deposits or in CO/CO2/O2 environments. The present study analyses the competing oxidation/sulfidation process in a humid atmosphere on two ferritic alloys with 2 and 9 % in weight chromium by in situ energy dispersive X-ray diffraction (EDXRD) and comparative tube furnace exposure using S16O2 and H2 18O atmosphere.
Ferritic high temperature alloys are widely used as boiler tube and heat exchanger materials in coal, biomass and co-fired power plants. All technologies have in common that the applied materials are exposed to different temperatures, process pressures and reactive atmospheres that lead to a change of the material properties and a further degradation of the material. Material changes caused by aging in highly corrosive and toxic gases such as SO2 are mainly studied ex situ after the reaction is finished. The solid material is deposited in the atmosphere for a certain period of time, and material changes are then examined by various microscopic techniques such as optical microscopy (OM), electron microprobe analysis (EMPA), scanning electron microscopy (SEM and TEM) and X-ray diffraction (XRD). Nevertheless, extensive efforts were made to study material changes of high temperature alloys under oxidizing and reducing atmospheres by environmental scanning electron microscopy or in situ TEM techniques However, the possibilities of microscopic in situ techniques are very limited for the use of highly corrosive and toxic gases such as SO2. Since Sulfur induced corrosion at temperatures relevant for coal and biomass fired power plants, which is causing breakaway oxidation and sulfide precipitation at grain boundaries, is still of scientific interest, the current work focuses on the effect of SO2 in an initial stage of corrosion of ferritic alloys. For the analysis of early stages of combined oxidation and sulphidation processes of Fe-Cr model alloys the usage of a light furnace to conduct a rapid reactive annealing experiment is feasible. Previous studies presented distinct results of the influence of chromium on early high temperature corrosion by SO2 by this technique and subsequent classical metallographic analyses. However, it is still not possible to trace the corrosion mechanism in real time by conducting single aging experiments. The current work introduces two different approaches to study the initial stages of high temperature oxidation processes by applying above state of the art X-ray diffraction and spectroscopy methods. One part focuses on the real time observation of the formation of corrosion products such as oxides and sulfides by energy dispersive X-ray diffraction (EDXRD). The potential of this technique to study crystallization and growth processes of thin films in a reactive environment in real time was previously shown for different compound semiconductors. This approach was now applied to follow oxidation and sulphidation processes of ferritic model alloys in SO2 and SO2/H2O environments. The diffraction signals of the X-rays were detected during the corrosion process and the peak area and positions were analyzed as a function of time. This procedure enables monitoring external oxide growth and material loss in real time in an early stage of corrosion.
The other part of the current work presents the possibilities of X-ray absorption near edge structure spectroscopy (XANES) to characterize oxide scales and their growth mechanisms. Precise phase identification and quantification of corrosion products in a multi-phase oxide/sulfide scale is a pre-requisite to understand diffusion paths of metal ions and gas components. It is a challenging task to distinguish structurally similar reaction products such as Fe3O4 and FeCr2O4 especially in thin films with texture effects by diffraction. To illustrate for example Cr-out diffusion of an alloy throughout an inner and external oxide scale the differentiation of Fe3O4 and FeCr2O4 is indispensable. XANES uses the photoionization effect at the metal absorption edge in an aging product and accesses by this structural and chemical information. The current work uses XANES at the Fe-K and Cr-K absorption edge to identify various aging products grown as thin layers on alloys after short time aging experiments. A reaction chamber for combining high temperature oxidation experiments with surface sensitive X-ray absorption near edge structure spectroscopy will be introduced and first results of XANES on scales at high temperatures will be presented.
Ferritic-martensitic alloys with 12-16 % Cr in weight are subject to devices for various energy systems, such as coal power plants and waste incineration plants. These materials are exposed to a highly corrosive environment which lead to a degradation of the material. Especially the simultaneous oxidation and sulfidation is thereby of special interest. Proper spatially resolved measurements that determine not only chemical compositions but phases are rare. However, precise phase identification and quantification of corrosion products within the multi-phase corrosion scales is a key aspect to understand diffusion paths of metal ions and gas ions/molecules. This study investigated Fe-Cr model alloys with Cr contents from 0 to 13 % in weight in 0.5 % SO2 and 99.5 % Ar atmosphere to aim in a fundamental and systematic analysis. Samples were aged at 650 °C for time scales from 12 h to 250 h. The results presented here correspond to depth dependent phase identification of oxide and sulphide phases in the corrosion scales by using X-ray absorption near edge spectroscopy (XANES). Per sample a series of ca. 20 spots (1-5 µm spot size) from scale-gas to scale-metal interface were measured. XANES spectroscopy was performed at the Fe-K edge (7.11 keV) on polished cross sections. The collected spectra were fitted to a combination of reference materials to quantify the present phases at different positions within the scale.The phase distribution differs with Cr content and the Cr diffusion through pure Fe-oxide and mixed Fe-Cr-oxide phases is discussed.
The high-entropy alloy (HEA) CrMnFeCoNi and the medium-entropy alloy (MEA) CrCoNi with a face-centered cubic (fcc) structure have excellent mechanical properties and are considered for high-temperature applications. Both materials were exposed under several oxidized atmospheres in a wide temperature range/regime. Mn-oxide (Mn3O4, Mn2O3) was mainly formed on the HEA and Cr2O3 on the MEA. The fast diffusion of manganese prevents the formation of a continuous chromia layer on CrMnFeCoNi in Ar-O2, Ar-H2O and Ar-SO2 at 800°C.
The Cantor alloy and his ternary subsystem CrCoNi were exposed in Ar-O2-H2O-SO2 at 800°C up to 96 h to clarify their oxidation behavior in a mixed atmosphere. The oxidized samples were analyzed by weight measurement, scanning electron microscopy (SEM), and X-ray diffraction analysis (XRD). It was found that mass gain of all samples increased with increasing exposure time. The oxidation rate of the Cantor alloy is significantly higher than that of the ternary alloy system.
Thermal spraying provides a rapid method for additive deposition of various ceramics as electrical insulation in applications where polymers are not suitable. New applications in complex shaped additive manufactured metal parts are emerging for example in large scale electrical devices. Microstructural and dielectric evaluation of coatings is crucial to the employment of such free-form processes. The properties and microstructure of the plasma sprayed alumina coatings are compared with dense reference samples of the same powder produced by spark plasma sintering (SPS). To obtain dense bulk samples from the coarse alumina powder for spray coating, SPS is used.
Samples are fabricated by atmospheric plasma spraying (APS) of commercially available alumina powder (d50 = 33 µm) on copper substrates and by SPS of the same powder. Microstructure and porosity were analyzed by optical microscopy and scanning electron microscopy (SEM). Phase compositions were determined by X-ray diffraction (XRD). Dielectric properties such as DC resistance, dielectric strength, dielectric loss, and relative permittivity were determined according to the standards. The microstructure and dielectric properties of the coating and bulk material are compared to assess whether the coating is suitable for use in electrical insulation application.
Additive manufacturing (AM) processes are opening new design possibilities for large scale electrical devices such as power generators. Conventional manufacturing methods use copper rods which are wrapped, vacuum impregnated, bend and welded. These processes are labor-intensive and time-consuming. The introduction of AM methods for manufacturing the copper conductor and electrical insulation can reduce the size of the generator head, the most complex part of the generator.
In this study, the electrical and dielectrical properties of additively deposited ceramic layers are investigated and compared with the properties of conventionally fabricated bulk ceramics. The ceramic layers are thermally deposited by atmospheric plasma spraying of a commercially available alumina powder. Bulk ceramics are fabricated by dry pressing and sintering of the same powder. Microstructure and porosity were analyzed by scanning electron microscopy (SEM). Electrical and dielectrical properties such as DC resistance, dielectric strength, dielectric loss, and relative permittivity were determined according to the standards.
The microstructures of sprayed and sintered alumina show significant differences with respect to grain form and porosity. The density of the bulk ceramic is lower than the density of the sprayed layer due to the coarse particle size (d50 = 33 μm). Therefore, data from dense samples of the same chemical composition but lower particle size alumina powder were used for comparison.
Ceramic multilayer technology is an attractive approach for the cost-effective fabrication of thermoelectric generators. Therefore, efforts are being made to co-sinter two promising thermoelectric oxides, namely calcium cobaltite and calcium manganate. In this study, calcium cobaltite, calcium manganate and release tapes were pressure assisted sintered. A major challenge here is the cracking of calcium manganate during cooling. A relationship between the properties of the release tape used in pressure-assisted sintering and the cracking behavior was observed experimentally.
To understand the origin of failure, formed reaction layers in the multilayer were analyzed by EDX and grazing incident XRD. Based on this analysis, bulk samples were prepared, and thermal expansion and Young's modulus and were determined thereon, if they were not known from the literature. The biaxial strength of the thermoelectric oxides was determined by the ball on three ball method.
The thermal stresses during cooling of different multilayer designs were estimated by finite element simulations. The stresses caused by the reaction layers turned out to be negligible. The FEM study indicated further, and a validation experiment proved, that the thickness of the release tape has the main effect on thermal stresses during cooling in single material. For best performance, the design of a thermoelectric multilayer generator needs to consider thermoelectric performance and thermal stresses during cooling.
Multilayer thermoelectric generators are a promising perspective to the conventional π-type generators. Ceramic multilayer technology is well established for production of microelectronics and piezo-stacks. Key features of ceramic multilayer technology are full-automation, cost-effectiveness, and the co-firing of all materials in one single step. This requires similar sintering temperatures of all used materials. The development of multilayer thermoelectric generators is a subject of current research due to the advantages of this technology. One of the challenges is the compatibility of the different materials with respect to the specific design.
The presented study compares three different designs of multilayer generators based on a given set of material properties. Dualleg, unileg and transverse multilayer generators are compared to conventional π-type generators., the designs are evaluated regarding the expected maximum output power and power density using analytical calculations and FEM simulations. Additionally, the complexity of the production process and material requirements are assessed and design optimizations to simplify production are discussed.
Besides the theoretical aspects, unileg multilayer generator prototypes were produced by tape-casting and pressure-assisted sintering. These prototypes are compared to other multilayer generators from literature regarding the power factors of the used material system and the power density. Improvements of the power output by design optimizations are discussed
Multilayered designs are an attractive approach towards cost-effective manufacturing of thermoelectric generators. Therefore, efforts are being made to co-fire two promising thermoelectric oxides, namely calcium cobaltite and calcium manganate. In this study, ceramic tapes, multilayer technology, and pressure-assisted sintering (PAS) were used. A major challenge for the PAS of low-sintered calcium manganate was cracking during cooling. A relationship between the properties of the release tape used during PAS and the cracking behavior was experimentally observed.
To understand the origin of failure, reaction layers in the multilayer were analyzed and thermal stresses during cooling were estimated by finite element (FE) simulations. Thermal expansion, elastic properties, and biaxial strength of the thermoelectric oxides and selected reaction layers were determined on separately prepared bulk samples. The analysis showed that the reaction layers were not the cause for cracking of calcium manganate.
Using the FE model, thermal stresses in different manganate multilayer designs with varying properties of the release tape were studied. The FEM study indicated, and a validation experiment proved that the thickness of the release tape has the main effect on thermal stresses during cooling in separately sintered calcium manganate.
The relaxation of macroscopic residual stresses in laser powder bed fused stainless steel 316L
(2021)
The processing of stainless steel 316L using the additive manufacturing process Laser Powder Bed Fusion (LPBF) can widen its field of application due to a strong increase in Yield strength, without making major compromises on the ductility nor its outstanding corrosion and oxidation properties. Furthermore, improved designs that either reduce the weight or optimise the function of a part can be obtained using LPBF. These benefits are however counterbalanced by the proneness of LPBF to inducing high Residual Stresses (RS) during manufacturing. The characterisation and monitoring of these RS are of paramount importance for the wider acceptance of the LPBF process. This study focuses on the relaxation of the initial macroscopic RS present in an LPBF 316L as-built prism that undergoes various routes of manufacturing steps to achieve different specimen geometries and stress relieving treatments. The RS are determined using Angle-Dispersive (AD) and Time-of-Flight (TOF) neutron diffraction. The results reveal high tensile RS close to the surfaces and compressive RS near the centre of the as-built parts. The reduction in size and change of geometry heavily impact the stress ranges of the remaining RS, with lower stress ranges in cylindrical shaped compared to rectangular shaped specimens. Also, the application of different stress relieving heat treatments showed that heat-treating temperatures above 800 °C are necessary to obtain a strong relaxation in LPBF 316L.
The dataset contains experimental mechanical data from complex service-like creep-fatigue experiments performed isothermally at 620 °C and a low strain amplitude of 0.2 % on tempered martensite-ferritic grade P92 steel. The data sets in text file format provide cyclic deformation (min. and max. stresses) and the total (hysteresis) data of all recorded fatigue cycles for three different creep-fatigue experiments: 1) a standard relaxation fatigue (RF) test with symmetrical dwell times of three minutes introduced at minimum and maximum strain, 2) a fully strain-controlled service-like relaxation (SLR) test combining these three-minute peak strain dwells with a 30-minute dwell in between at zero strain, and 3) a partly stress-controlled service-like creep (SLC) test combining the three-minute peak strain dwells with 30-minute dwells at constant stress.
Further information on data and data acquisition, analysis, and experimental details are given in “Experimental Data from Service-Like Creep-Fatigue Experiments on Grade P92 Steel”, submitted to Data in Brief. Additional analyses of these datasets, as well as experimental findings and discussions are presented in “Creep-Fatigue of P92 in Service-Like Tests with Combined Stress- and Strain-Controlled Dwell Times”, submitted to International Journal of Fatigue.
Tempered martensite-ferritic steels, such as the grade P92 steel studied in this contribution, exhibit pronounced macroscopic cyclic softening under isothermal low-cycle fatigue (LCF) and non-isothermal thermomechanical fatigue (TMF) conditions, which is considered to be the predominant degradation mechanism in high-temperature fatigue in this and other material groups. However, such softening processes are highly complex since microscopic (e.g., recovery) and macroscopic (e.g., crack initiation and growth), as well as global and local effects superimpose, especially under creep-fatigue conditions. In this contribution, we discuss the cyclic deformation and softening behavior of P92 in strain-controlled LCF, in-phase (IP) TMF, and out-of-phase (OP) TMF tests with and without dwell times in the temperature range from 300 °C to 620°C. EBSD-based dislocation analysis on various fatigued material states confirms the continuous redistribution and annihilation of geometrically necessary dislocations in all studied states, which can be quantitatively correlated with macroscopic softening despite different damage mechanisms for different test types. Deviations from this correlation are observed for OP TMF and LCF with dwell times, i.e., for conditions where optical microscopy reveals pronounced crack-oxidation interactions at the specimen surfaces.
Due to the advantages of additive manufacturing (AM), it has been increasingly integrated into many industrial sectors.
The application of AM materials for safety-critical parts requires the detailed knowledge about their microstructure stability under thermo-mechanical or mechanical load and knowledge on ageing process mechanisms. Ageing processes are characterized by change of the material microstructure that is to be initially investigated. This work deals with the Investigation of 316L stainless steel manufactured by selective laser melting (SLM). Describing Parameters must be defined and applied on the microstructure of these materials in their initial state and after loads were applied. The findings of this work form the basis for the investigation of AM material ageing.
Microstructure ageing of stainless steel AISI 316L manufactured by selective laser melting (SLM)
(2019)
Additive manufacturing (AM) processes, such as SLM, offer a variety of advantages compared to conventional manufacturing. Today AM parts are still comparatively less cost-effective if they are manufactured in large quantities. To make the AM parts more cost-efficient, the AM process has to be improved. It requires a good understanding of microstructure formation, microstructure-property-relations and ageing processes affected by different loads.
In this work the ageing behavior of SLM manufactured AISI 316L stainless steel is evaluated. The microstructure effected by mechanical, thermal and corrosive loads are investigated and compared to as-built microstructure. Tensile tests are used for mechanical ageing. For thermal and corrosive loads the typical application conditions of 316L apply. The methods of microstructure investigation include SEM, TEM, CT and EBSD. The main object of this work is the description of microstructure and ageing processes of AM parts.
Additive manufacturing (AM) offers diverse advantages compared to conventional manufacturing. In this work the microstructure of austenitic steel 316L, manufactured with Selective Laser Melting (SLM), was analyzed and compared to microstructure of 316L hot rolled material. Methods used for analysis are microprobe, optical microscopy and electron backscatter diffraction.
Among the very few techniques to localize hydrogen (H) at the microscale in steels, Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was proven to be a reliable tool. The necessity to detect hydrogen stems from its deleterious effects in metals, that are often used as structural components and to obtain better understanding of the underlying metallurgical mechanisms of hydrogen embrittlement (HE) which are still unclear.
Austenitic stainless steels are nowadays commonly used in a wide variety of application, from hydrogen transport and storage facilities to petrochemical and offshore applications where they are exposed to aggressive environments and therefore prone to HE. One of the greater risks in the austenitic class is the embrittlement of the material due to the instability of the γ austenite and its transformation into a brittle α martensitic phase. This transformation takes place due to the local stresses that are induced by the uptake of hydrogen during service. Nonetheless, it was shown that this transformation can occur as an artefact during SIMS analysis itself where Cs-sputtering is necessary not only to remove surface contaminations but mainly to enhance H/D secondary ion yield.
In the following contribution we show the influence of different sputtering conditions on AISI 304L austenitic stainless steel in order to distinguish the artefact from the hydrogen induced transformation. The material was charged electrochemically in a deuterium based electrolyte. Deuterium (D) must be in these experiments as a replacement for hydrogen which cannot be used because adsorbed hydrogen superimposes hydrogen originating from charging the sample in the SIMS images. ToF-SIMS analyses were conducted by ToF SIMS IV (IONTOF GmbH, Münster, Germany). The experiments were carried out on deuterium charged and non-charged samples. The structural characterization was carried out by SEM and EBSD examinations before and after charging, both with a Leo Gemeni 1530VP field-emission scanning electron microscope and a Zeiss Supra 40 instrument (Carl Zeiss Microscopy GmbH, Oberkochen, Germany). The results showed that the use of 1keV Cs+ beam induces stacking faults while higher sputter beam energies results in γ→α transformation.
Performing mechanical tests at high temperatures is a nontrivial issue: Compared to room temperature testing, additional phenomena like time-dependent Deformation processes and oxidation effects raise the complexity of the material’s response, while more sophisticated test setups and additional control parameters increase the number of potential sources of error. To a large extent, these complications can be overcome by carefully following all recommendations given in the respective high temperature testing standards, but more comprehensive background information helps to identify points of specific importance in particular test campaigns. In this chapter, an overview is given on general high temperature testing issues like the appropriate choice of experimental equipment and key aspects of temperature measurement. In subsequent sections, the major static and dynamic high temperature test methods are reviewed and their Special features, as compared to testing at room temperature, are highlighted based on example data sets. Influences of specimen size and environmental effects are shortly outlined in a concluding section. In the whole chapter, a focus is set on testing of “classical” metallic high temperature materials, but many considerations are equally valid for testing of intermetallics, composites, and high temperature ceramics.
In typical material oriented research projects numerous types and sources of data need to get connected to form the final outcome. The data-structures have to be described in a manner semantically concise enough so that all participants share the meaning and at the same time flexible enough to allow connecting findings and facts that have not been connected before.
The present contribution describes the approach that is being taken in a public funded research project with two cooperating research institutes. The aim of the data-management solution is to describe and interlink three main entity types: material entities like a test specimen that is under observation, immaterial entities like a fatigue life model and processes that generate and transform the immaterial and material entities.
The shared understanding of what is described by the data is achieved by referring to existing linked data resources. In addition a common thesaurus that is subject to ongoing discussion is used for concepts and terms that need precision beyond publicly available concept descriptions. The data associated with the entities and processes and entities is rather small and well structured. The entities and processes covered by the vocabularies are typical to laboratories performing fatigue testing and microstructure analysis. Through the interlinking of the entities and processes it becomes possible to intuitively understand the knowledge that is accumulating in the database. For example it is easy to trace the history of a creep test specimen starting from the chemical composition that has been analyzed for the heat, continuing with the heat treatment of the material, going into the creep test itself with the associated creep data and finally finding the transmission electron microscopy images that have been taken from the crept sample.
The presented approach is prototypical way to tackle the sustainable management of structured open research data. Open questions remain for example with the management of attributions, the acceptance of an increased effort in data creation and the access control to specific regions of the data. On the other hand the approach sketches what added value can be created, if the community adopts and contributes to the linked data principles.
The mechanical strength of wrought high-strength aluminum alloys is essentially based on precipitation hardening, possibly in combination with prior forming, e. g. by stretching. Important parameters for achieving an optimum combination of hardness, strength, ductility, toughness, and further properties such as corrosion resistance are age-hardening temperature and time.
During thermal (mechanical) treatment, nucleation and growth of precipitates takes place, leading to the desired degree of hardening. In aluminum alloys, precipitation sequences are usually passed through, i. e. a sequence of metastable precipitates is formed before the stable phase can precipitate. The optimum combination of properties is therefore based on a certain (optimum) microstructure, which can, however, change during the use of a component, since the microstructure is not stable. This happens in particular when the operating temperatures are close to the aging temperature and/or the operating times are sufficiently long. An external mechanical load may accelerate the processes. The presentation gives some examples for this.
The heat-resistant cast iron EN-GJSA-XNiSiCr35-5-2 (Ni-Resist D-5S) was investigated for its fatigue crack growth behavior at room and high temperatures. Force-controlled tests were carried out at constant temperatures (20 °C, 500 °C, 700 °C) without and with hold time and different load ratios. The crack growth behavior was also characterized under TMF loading (Tmin = 400 °C, Tmax = 700 °C) by applying IP and OP conditions and different load ratios. Three different techniques were combined to monitor crack growth: potential drop, thermography, and compliance method. The effect of the different loading conditions on the fatigue crack growth behavior will be presented and discussed.
The life time of mechanical components in high temperature applications is basically determined by their workings. Corrosion determines the loss of material corresponding to the loss of the effective load-bearing section and consequently increasing stress levels. To improve the material selection for such applications a numerical life prediction corrosion model for different alloys and environments is needed. Based on the ferritic alloys FeCr and FeCrCo a first quantitative model is to be developed. For this purpose, the alloys are aged at 600 °C, 650 °C and 700 °C in synthetic air under normal pressure for between 10 and 240 hours. The first objective is to establish a quantitative relationship between the oxidation rate as a function of composition and microstructure of the alloys. The influence of the inner interface as an essential parameter for transport by diffusion on the oxidation kinetics is discussed in this paper.
The life time of mechanical components in high temperature applications is basically determined by their workings. Corrosion determines the loss of material corresponding to the loss of the effective load-bearing section and consequently increasing stress levels. To improve the material selection for such applications a numerical life prediction corrosion model for different alloys and environments is needed. Based on the ferritic alloys FeCr and FeCrCo a first quantitative model is to be developed. For this purpose, the alloys are aged at 600°C, 650°C and 700°C in synthetic air under normal pressure for between 10 and 240 hours. The first objective is to establish a quantitative relationship between the oxidation rate as a function of composition and microstructure of the alloys. The influence of the inner interface as an essential parameter for transport by diffusion on the oxidation kinetics is discussed in this presentation.
The aim of the task area Materials Data Infrastructure (TA-MDI) of the consortium Materials Science and Engineering (MatWerk) of National Research Data Infrastructure (NFDI) is to shape scientific datasets obtained through the Participant Projects (PPs) from a data management perspective conforming to the FAIR principles, making use of the FAIR Digital Object (FAIR DO) concept, including structured metadata and storage solutions. As an example, they apply PP18 (BAM) as a use case to demonstrate the proposed technical workflow.
Within NFDI-MatWerk (“National Research Data Infrastructure for Material Sciences”/ “Nationale Forschungsdateninfrastruktur für Materialwissenschaften und Werkstofftechnik“), the Task Area Materials Data Infrastructure (TA-MDI) will provide tools and services to easily store, share, search, and analyze data and metadata. Such a digital materials environment will ensure data integrity, provenance, and authorship. The MatWerk consortium aims to develop specific solutions jointly with Participant Projects (PPs), which are scientific groups or institutes covering different domains, from theory and simulations to experiments. The Data Exploitation Methods group of the Karlsruhe Institute of Technology-Steinbuch Centre of Computing, as part of TA-MDI, is developing specific solutions in close collaboration with three PPs.
PP07, together with the University of Stuttgart, aims at the image-based prediction of the material properties of stochastic microstructures using large-scale supercomputers. PP13, in cooperation with the University of Saarland, focuses on tomographic methods at various scales in materials research. PP18, together with the Federal Institute for Materials Research and Testing (“Bundesanstalt für Materialforschung und -prüfung”), aspires to define the criteria for materials reference datasets and usage analytics.
The requirements and goals are comparable for each PP: their research outputs, which are scientific datasets, should conform to the FAIR (Findable, Accessible, Interoperable, Reusable) principles. We aim to shape them from a data management perspective making use of the FAIR Digital Object concept, including structured metadata and storage solutions. The results will be a blueprint which will act as a reference for future datasets. Even though the collaboration is in an early stage, the initial steps already show the added value of this approach.
This research has been supported by the Federal Ministry of Education and Research
(BMBF) – funding code M532701 / the Deutsche Forschungsgemeinschaft (DFG, German
Research Foundation) - project number NFDI 38/1, project no. 460247524.
Currently, calcium manganate CaMnO3 and calcium cobaltite Ca3Co4O9 are being investigated as n-type resp. p-type semiconducting materials as oxidation- and temperature-resistant thermoelectric materials for oxide multilayer thermoelectric generators (TEGs). In order to manufacture multilayer TEGs, pressure-assisted sintering processes at high temperatures are necessary to achieve optimal thermoelectric material properties. To realize TEGs in planar film technology, another method to obtain dense ceramic layers directly from the synthesized starting powders without a subsequent high temperature step is emerging recently: the powder aerosol deposition (PAD) method. In the present work, it is investigated whether PAD is suitable to produce dense ceramic films from Sm-doped CaMnO3 and Ca3Co4O9 powders. The resulting thermoelectric properties are characterized as a function of temperature.
CaMnO3 powder could successfully be processed by PAD with resulting layer thicknesses of 5- 6 µm without any high-temperature sintering steps of the films. The electrical conductivity and the Seebeck coefficient of the films were determined in-plane from room temperature to 600 °C in air. The results show a Seebeck coefficient of around -200 µV/K, which is comparable to results of pressed and sintered bars. At 400 °C, the electrical conductivity corresponds to the conductivity of the bar. At higher temperatures the conductivity is better than with the reference. Below 400°C, the electrical conductivity is somewhat lower than that of the reference sample, a mild thermal treatment of the PAD layer improves it. It is expected that the thermal conductivity of the PAD film will be lower compared to the bars due to the nano-crystalline film morphology. This should result in a significantly increased ZT value for the PAD layers and a higher efficiency of the TEG.
The work shows that both CaMnO3 and Ca3Co4O9 can be successfully processed by PAD, and the PAD films show comparable thermoelectric properties.
Oxide thermoelectric semiconducting materials like p-type calcium cobaltite Ca3Co4O9 are investigated as oxidation- and temperature-resistant thermoelectric materials for thermoelectric generators (TEGs). To realize TEGs in planar film technology, the powder aerosol deposition (PAD) method is emerging recently. PAD is a method to obtain dense ceramic films directly from the synthesized starting powders without a subsequent high temperature step.
In the present work, Ca3Co4O9 (CCO) powders are processed by PAD to ceramic films at room temperature. The thermoelectric properties of the films (film thickness 10 – 20 µm) are characterized from room temperature to 900°C. Additionally, the layer morphology and texture of the films will be investigated.
As result, the Seebeck coefficient of the CCO-PAD film is comparable to pressed and sintered CCO-bulk materials during the 1st heating cycle to 900°C. The morphology of the films after the thermal treatment shows strong aligned crystallites resulting in a strong texture of the films. The electrical conductivity increases strongly during the 1st heating cycle to 900°C and stays almost constant afterwards. Compared to CCO-bulks, the films provide higher electrical conductivity which could be explained by the oriented crystal growth in-plane direction of the film.
The relationship between thermoelectric properties and layer morphology as a function of thermal annealing parameters will be further investigated.
Modern wind turbine rotor blades consist of sandwich shell segments made from glass fiber reinforced polymers. During manufacturing, defects can arise which could lead to failure of the whole component under dynamic mechanical and thermal loads. Hence during operation defects can arise which, if detected, can be repaired locally and in-situ by applying repair patches instead of taking the whole rotor blade down and repair it remotely. This method is much more time and cost effective, since the shut-down time of the energy converter is limited to a minimum. These repair patches can, however, also lead to new defects if not applied optimally. Therefore, it is necessary to control the quality of the repair patches to ensure the best possible restoration of structural integrity of the component. As a rotor blade is an object with a large aspect ratio, X-ray laminography is predestined to provide 3D information of the objective volume. To enhance the amount of information gained from laminographic reconstruction, we use in this study a photon counting and energy discriminating X-ray detector and apply a material decomposition algorithm to the data. By inherently separating the incident spectra within the detection process into two distinct energy bins, the basis material decomposition can provide material resolved images. Choosing glass and epoxy resin as basis materials and numerically solving the inverse dual-energy equation system, the reconstructed laminographic datasets contain highly valuable information about the distribution of the basis materials within the structure. Furthermore, cross- artifacts arising from the limited angle of the projection data can be reduced by this method which allows to investigate structures that were hidden underneath the artefacts.
Modern wind turbine rotor blades consist of sandwich shell segments made from glass fiber reinforced polymers. During manufacturing, defects can arise which could lead to failure of the whole component under dynamic mechanical and thermal loads. Hence during operation defects can arise which, if detected, can be repaired locally and in-situ by applying repair patches instead of taking the whole rotor blade down and repair it remotely. This method is much more time and cost effective, since the shut-down time of the energy converter is limited to a minimum. These repair patches can, however, also lead to new defects if not applied optimally. Therefore, it is necessary to control the quality of the repair patches to ensure the best possible restoration of structural integrity of the component. As a rotor blade is an object with a large aspect ratio, X-ray laminography is predestined to provide 3D information of the objective volume. To enhance the amount of information gained from laminographic reconstruction, we use in this study a photon counting and energy discriminating X-ray detector and apply a material decomposition algorithm to the data. By inherently separating the incident spectra within the detection process into two distinct energy bins, the basis material decomposition can provide material resolved images. Choosing glass and epoxy resin as basis materials and numerically solving the inverse dual-energy equation system, the reconstructed laminographic datasets contain highly valuable information about the distribution of the basis materials within the structure. Furthermore, cross- artifacts arising from the limited angle of the projection data can be reduced by this method which allows to investigate structures that were hidden underneath the artefacts.
The high-temperature corrosion behavior of the medium-entropy alloy Cr33Co33Ni33 (MEA) and the high-entropy alloy Fe20Cr20Co20Ni20Mn20 (HEA) in a mixed gas atmosphere of 10% H2O-2% O2 -0.5% SO2 + Ar as carrier gas [Vol.%] at 800 °C with duration times of t = 24h, 48h and 96h was investigated. Both alloys have a single-phase fcc microstructure. The oxidation kinetics of the HEA-CrMnFeCoNi roughly followed a linear rate law and a slow oxide growth was observable for the MEA-CrCoNi. The scale thickness of the corrosion layer in the quinary alloy increased with exposure time, while the scale thickness in the ternary alloy remained constant at around 1 µm. The MEA-CrCoNi developed a protective Cr2O3 layer with minor buckled parts. Co,Ni-chromite (Co,Ni)Cr2O4 was detected by XRD in minor amounts. The scale on HEA-CrMnFeCoNi displayed a triplex structure of a thin, continuous, inner Cr2O3 layer, a dense, intermediate Mn3O4 layer, and a thick, outer, porous layer consisting of Mn3O4 and MnSO4. Sulphides were only identified in the matrix of HEA-CrMnFeCoNi. Thermodynamic equilibrium calculations with FactSage (Log(S2) vs. Log(O2), ΔG of reactions) are in good agreement with these observations. The intense diffusion of Cr in the ternary alloy leads to an immediate formation of a protective Cr2O3 layer. The fast diffusion of Mn through the bulk HEA material and through the formed Cr2O3 layer compared to the other alloying elements is considered as the rate-limiting process.
The study presented here focusses on a systematic analysis of oxidation mechanisms of the well-known Cr20Mn20Fe20Co20Ni20 alloy and one of its ternary sub-system Cr33.3Co33.3Ni33.3 which were reported in the literature to exhibit attractive mechanical properties. Both alloys are single phase fcc prior to oxidation and were simultaneously exposed to different oxygen containing atmospheres at 700° C and 800° C for durations up to 288 h. Cr20Mn20Fe20Co20Ni20 showed poor oxidation resistance at high temperatures due to its high amount of manganese leading to the formation of non-protective Mn-oxide scales. In contrast, a relatively homogeneous and protective chromia layer was found to form on CrCoNi at 700° C and 800° C after each exposure time. Mass change-, SEM- and XRD analysis of the oxide layers were performed in the present study and provide a better understanding of the oxidation mechanisms as well as the impact of the alloy composition on oxidation behavior.
To apply high-entropy alloys (HEA) of the CrMnFeCoNi family in challenging atmospheres, their degradation behavior under harsh environments needs to be investigated. Oxidation studies to HEAs have not been extensively investigated and most of them are concentrated on environments like synthetic air, laboratory air, CO/CO2, O2 and H2O atmospheres. Main corrosion products which were identified after aging times of up to 100 h are Mn2O3 (≤800°C) and Mn3O4 (≥800°C).
Another corrosive medium in high temperature applications is SO2, which preferentially forms sulfides on commercial steels for example. These can be occurred both in the oxide layer and at the oxide/metal interface. For instance, on Fe-Cr based alloys sulfides (Cr5S6) were detected along grain boundaries and their number increases with exposure time and Cr-content in the alloy. These sulfides show an increased hardness, compared to the bulk alloy, and cause an embrittlement of the grain boundaries. This is a serious material degradation phenomenon, now addressed for the case of HEAs.
In the present study metal sulfides were identified after corrosion of the HEA CrMnFeCoNi alloy in an Ar-0.5vol.%SO2 atmosphere at 800°C for 24 h, 48 h, 96 h and 192 h exposure time. After all three duration times, a thin non-protective Cr2O3 layer has formed at the oxide/alloy interface. At the gas side a thick Mn3O4 layer with local voids containing sulfur could be detected by SEM-EDS analysis. Furthermore, S precipitates could be detected in the bulk material near the surface. These sulfides were characterized in detail by scanning and transmission electron microscopy. Based on these results, a model for grain boundary sulfidation of high-entropy alloy CrMnFeCoNi is discussed.
High- and medium-entropy alloys (HEAs and MEAs) constitute a new class of materials. Those with a face-centered cubic (fcc) structure from the Cr-Mn-Fe-Co-Ni system have excellent mechanical properties and are considered for high-temperature applications since diffusion in these alloys was reported to be sluggish. However, their corrosion resistance at high temperatures must still be evaluated to further qualify them for such kinds of applications. Various groups studied the oxidation behavior of HEAs and MEAs under (dry) laboratory and artificial air as well as CO2/CO mixtures in different temperature ranges. Adomako et al. carried out oxidation tests in dry air between 800 °C and 1000 °C for 24 h in equiatomic CrCoNi, CrMnCoNi, and CrMnFeCoNi alloys. The authors showed that CrCoNi exhibits the best corrosion resistance at 800 °C due to the formation of a protective Cr2O3 layer. The matrix below the oxide scale was reported to be correspondingly depleted in Cr. It was further shown that the addition of Mn and Fe to CrCoNi changes the phase composition of the oxide scale at 800 °C. A Mn2O3 layer was grown during oxidation on CrMnCoNi and CrMnFeCoNi and a Cr2O3 scale was formed at the matrix/oxide scale interface. Beneath these oxide layers, Mn- and Cr-depleted zones were detected. These phase morphologies demonstrate the inward diffusion of oxygen and outward diffusion of Cr and Mn resulting in the formation of Cr2O3 and Mn2O3. In the present study, the corrosion resistance of CrMnFeCoNi and CrCoNi were confirmed and additionally characterized under further oxidizing atmospheres at 800 °C including Ar-2 Vol.% O2, Ar-2 Vol.% H20, and Ar-2 Vol.% SO2 mixtures.
High- and medium-entropy alloys (HEAs and MEAs) constitute a new class of materials. Those with a face-centered cubic (fcc) structure from the Cr-Mn-Fe-Co-Ni system have excellent mechanical properties and are considered for high-temperature applications since diffusion in these alloys was reported to be sluggish. However, their corrosion resistance at high temperatures must still be evaluated to further qualify them for such kinds of applications.
Various groups studied the oxidation behavior of HEAs and MEAs under (dry) laboratory and artificial air as well as CO2/CO mixtures in different temperature ranges. CrCoNi exhibits the best corrosion resistance at 800 °C due to the formation of a protective Cr2O3 layer. The matrix below the oxide scale was reported to be correspondingly depleted in Cr. It was further shown that the addition of Mn and Fe to CrCoNi changes the phase composition of the oxide scale at 800 °C. A Mn2O3 layer was grown during oxidation on CrMnCoNi and CrMnFeCoNi and a Cr2O3 scale was formed at the matrix/oxide scale interface. Beneath these oxide layers, Mn- and Cr-depleted zones were detected. These phase morphologies demonstrate the inward diffusion of oxygen and outward diffusion of Cr and Mn resulting in the formation of Cr2O3 and Mn2O3.
In the present study, the corrosion resistance of CrMnFeCoNi and CrCoNi were confirmed and additionally characterized under further oxidizing atmospheres at 800 °C including Ar-2 Vol.% O2, Ar-2 Vol.% H20, and Ar-2 Vol.% SO2 mixtures.
The interest to additively manufacture Nickel-based superalloys has substantially grown within the past decade both academically and industrially. More specifically, additive manufacturing processes such as laser powder bed fusion (LPBF) offer the ability to produce dense parts within a single manufacturing step. In fact, the exceptional freedom in design associated with the layer-based nature of the processes is of particular interest for the complex shapes typically required in turbine applications. In certain cases, the overall part performance can be achieved by tailoring the microstructure and the crystallographic texture to the specific application. However, these advantages must be paid at a price: the large local temperature gradients associated with the rapid melting and solidification produce parts that inherently contain large residual stress in the as-manufactured state. In addition, the presence of pores in the final part may further affect the in-service part failure. As among Nickel-based alloys Inconel 718 exhibits excellent weldability, this alloy has been widely studied in open research in the domain of LPBF. However, significant microsegregation of the heavier alloying elements such as Niobium and Molybdenum accompanied by dislocation entanglements may preclude the application of conventional heat treatment schedules. Therefore, different post processing heat treatments are required for laser powder bed fused Inconel 718 as compared to conventional variants of the same alloy.
In this study, we investigated two different heat treatment routes for LPBF Inconel 718. In a first routine, the samples were stress relieved and subsequently subjected to hot isostatic pressing (HIP) followed by a solution heat treatment and a two-step age (referred to as FHT). In a second routine, the samples were subjected to a single-step direct age post stress relieving heat treatment (referred to DA). We investigated the consequences of such heat treatment schedules on the microstructure, texture, and mechanical behavior. We show that by applying a DA heat treatment the typical columnar microstructure possessing a crystallographic texture is retained, while an equiaxed untextured microstructure prevails in case of an FHT heat treatment. We further evaluate how these heat treatments affect the mechanical behaviour on the macroscopic and microscopic scale.
Additive manufacturing methods such as laser powder bed fusion (LPBF) allow geometrically complex parts to be manufactured within a single step. However, as an aftereffect of the localized heat input, the rapid cooling rates are the origin of the large residual stress (RS) retained in as-manufactured parts. With a view on the microstructure, the rapid directional cooling leads to a cellular solidification mode which is accompanied by columnar grown grains possessing crystallographic texture. The solidification conditions can be controlled by the processing parameters and the scanning strategy. Thus, the process allows one to tailor the microstructure and the texture to the specific needs. Yet, such microstructures are not only the origin of the mechanical anisotropy but also pose metrological challenges for the diffraction-based RS determination. In that context the micromechanical elastic anisotropy plays an important role: it translates the measured microscopic strain to macroscopic stress. Therefore, it is of uttermost importance to understand the influence of the hierarchical microstructures and the texture on the elastic anisotropy of LPBF manufactured materials.
This study reveals the influence of the build orientation and the texture on the micro-mechanical anisotropy of as-built Inconel 718. Through variations of the build orientation and the scanning strategy, we manufactured specimens possessing [001]/[011]-, [001]-, and [011]/[111]-type textures. The resulting microstructures lead to differences in the macroscopic mechanical properties. Even further, tensile in-situ loading experiments during neutron diffraction measurements along the different texture components revealed differences in the microstrain response of multiple crystal lattice planes. In particular, the load partitioning and the residual strain accumulation among the [011]/[111] textured specimen displayed distinct differences measured up to a macroscopic strain of 10 %. However, the behavior of the specimens possessing [001]/[011]-and [001]-type texture was only minorly affected. The consequences on the metrology of RS analysis by diffraction-based methods are discussed.
Laser powder bed fusion (PBF-LB/M) of metallic alloys is a layer wise additive manufacturing process which provides significant scope for more efficient designs of components, benefiting performance and weight, leading to efficiency improvements for various sectors of industry. However, to benefit from these design freedoms, knowledge of the high produced induced residual stress and mechanical property anisotropy associated with the unique microstructures is critical. X-ray and neutron diffraction are considered the benchmark for non-destructive characterization of surface and bulk internal residual stress. The latter, characterized by the high penetration power in most engineering alloys, allows for the use of diffraction angle close to 90° enabling a near cubic sampling volume to be specified. However, the complex microstructures of columnar growth with inherent crystallographic texture typically produced during PBF-LB/M of metallics present significant challenges to the assumptions typically required for time efficient determination of residual stress. These challenges include the selection of an appropriate set of diffraction elastic constants and a representative strain-free reference for the material of interest. In this presentation advancements in the field of diffraction-based residual stress analysis of L-PBF Inconel 718 will be presented. The choice of an appropriate set of diffraction-elastic constants depending on the underlying microstructure will be described.
In this presentation, the results of the determination of the diffraction and single-crystal elastic constants of laser powder bed fused Inconel 718 are presented. The analysis is based on high-energy synchrotron diffraction experiments performed at the Deutsches Elektronen-Synchrotron. It is shown that the characteristic microstructure of laser powder bed fused Inconel 718 impacts the elastic anisotropy and therefore the diffraction and single-crystal elastic constants. Finally, the consequences on the diffraction-based residual stress determination of laser powder bed fused Inconel 718 are discussed.
The aim of a fractographic investigation is the evaluation of macroscopic and microscopic fracture surface characteristics and, as a result, the determination of the fracture mechanism of a component from a failure case. The basis for such evaluations of fracture characteristics comes from actual comparative mechanical testing and from the literature. A fractographic analysis can be very complex and, in any case, requires considerable experience. In the IGF project "iFrakto", software is being developed that quantitatively determines fracture characteristics and fracture mechanisms utilizing digitized expert knowledge, machine learning, and standard 2D and topographical data from SEM imaging. Topographical data are obtained from 4QBSE detector using shape-from-shading technology. In the medium term, a software tool should provide knowledge-based suggestions for the evaluation of fracture surfaces in real time during SEM work or at subsequent evaluation. As a basis for this, round robins were carried out among fractographers in order to create a knowledge base, to query the practice-relevant requirements for such tools and to carry out first practical tests. Actual results are presented and the relevance of the evaluation strategy is evaluated.
In order to observe the effect of the aggregate phases between 2 mm and 16 mm without overlap with rheological effects induced by the cement hy-dration and without interactions with a threshold fine sand particle size that affects both, paste and aggregates, rheological experiments were conducted on a limestone filler based paste mixed with aggregates up to 16 mm. Vari-ous aggregate fractions were blended and mixed with the replacement paste in different volumetric ratios.
The dry aggregates’ flow coefficients were determined and compared to yield stress and plastic viscosity values at different aggregate volume fractions. The results indicated that the flow coefficient is not a suitable parameter to predict the performance of the aggregates in the paste. It was shown that the yield stress of pastes is largely determined by the blend of different aggregate fractions, while the plastic viscosity to large extend depends upon the coars-est aggregate fraction.
Based on the results, ideal aggregate composition ranges for minimised yield stress are presented. For the plastic viscosity no such grading curves to achieve minimum values could be found, but high viscosity curves are identified.
The dataset provided in this repository comprises data obtained from a series of characterization tests performed to a sheet of typical S355 (material number: 1.0577) structural steel (designation of steel according to DIN EN 10025-2:2019). The tests include methods for the determination of mechanical properties such as, e.g., tensile test, Charpy test and sonic resonance test. This dataset is intended to be extended by the inclusion of data obtained from further test methods. Therefore, the entire dataset (concept DOI) comprises several parts (versions), each of which is addressed by a unique version DOI.
The data were generated in the frame of the digitization project Innovationplatform MaterialDigital (PMD) which, amongst other activities, aims to store data in a semantically and machine understandable way. Therefore, data structuring and data formats are focused in addition to aspects in the field of material science and engineering (MSE). Hence, this data is supposed to provide reference data as basis for experimental data inclusion, conversion and structuring (data management and processing) that leads to semantical expressivity as well as for MSE experts being generally interested in the material properties and knowledge.
The dataset provided in this repository comprises data obtained from a series of full-notch creep tests (FNCT) performed on selected high-density polyethylene (PE-HD) materials (for further details, see section 1 Materials in this document) in accordance with the corresponding standard ISO 16770.
The FNCT is one of the mechanical testing procedures used to characterize polymer materials with respect to their environmental stress cracking (ESC) behavior. It is widely applied for PE-HD materials, that are predominantly used for pipe and container applications. It is based on the determination of the time to failure for a test specimen under constant mechanical load in a well-defined and temperature controlled liquid environment. The test device used here also allows for continuous monitoring of applied force, specimen elongation and temperature.
PMD Core Ontology (PMDco)
(2023)
The PMD Core Ontology (PMDco) is a comprehensive framework for representing knowledge that encompasses fundamental concepts from the domains of materials science and engineering (MSE). The PMDco has been designed as a mid-level ontology to establish a connection between specific MSE application ontologies and the domain neutral concepts found in established top-level ontologies. The primary goal of the PMDco is to promote interoperability between diverse domains. PMDco's class structure is both understandable and extensible, making it an efficient tool for organizing MSE knowledge. It serves as a semantic intermediate layer that unifies MSE knowledge representations, enabling data and metadata to be systematically integrated on key terms within the MSE domain. With PMDco, it is possible to seamlessly trace data generation. The design of PMDco is based on the W3C Provenance Ontology (PROV-O), which provides a standard framework for capturing the generation, derivation, and attribution of resources. By building on this foundation, PMDco facilitates the integration of data from various sources and the creation of complex workflows. In summary, PMDco is a valuable tool for researchers and practitioners in the MSE domains. It provides a common language for representing and sharing knowledge, allowing for efficient collaboration and promoting interoperability between diverse domains. Its design allows for the systematic integration of data and metadata, enabling seamless traceability of data generation. Overall, PMDco is a crucial step towards a unified and comprehensive understanding of the MSE domain. PMDco at GitHub: https://github.com/materialdigital/core-ontology
Due to the diversity of materials and the processes associated with their production and use, the complexity of the lifecycles of materials and the multitude of academic and industrial researchers participating in generation of data for material design impose a huge challenge. The topical goal of digitalizing materials and processes can only be adequately addressed by consolidating the efforts of all stakeholders in this field. There are many scattered activities, but there is a demand for an elimination of redundancies as well as an advance in acceptance and a common basis in the digitalization of materials. Furthermore, data analysis methods play an important role in both, the experimental and simulation-based digital description of materials, but they have been poorly structured so far.
Therefore, the two joint projects Platform Material Digital (PMD, materialdigital.de) and Materials open Laboratory (Mat-o-Lab, matolab.de) aim to contribute to a standardized description of data processing methods in materials research. Besides stimulating the formation of a collaborative community in this respect, their main technical goals are the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications. In this regard, data management in accordance with the FAIR (findability, accessibility, interoperability, reuseability) principles is addressed. There is a common agreement in the scientific community following current discussions that data is supposed to be conform to these principles. This includes storage, processing and querying of data in a preferably standardized form.
To meet the challenge to contextualize material data in a way that is consistent with all stakeholders, all necessary information on the condition of the material including production and application-related changes have to be made available via a uniform, machine-readable description. For this purpose, ontologies are to be used since they allow for machine-understandable knowledge representations and conceptualizations that are needed for data management and the digitalization in the field of materials science.
As first efforts in PMD and Mat-o-Lab, application ontologies are created to explicitly describe processes and test methods. Thereby, the well-known tensile test of metals at room temperature was described ontologically in accordance with the respective ISO standard 6892-1:2019-11.
The efforts in creating this tensile test application ontology are shown in this presentation. Especially, the path of ontology development based on standards to be pursued is focused, which is in accordance with the generic recommendations for ontology development and which is supposed to be exemplary for the creation of other application ontologies.
Data analysis methods play an important role in both the experimental and simulation-based digital description of materials but have so far been poorly structured. The platform Material Digital (PMD) is supposed to contribute to a standardized description of data processing methods in materials research. The goal is the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications.
Therefore, application ontologies are created to explicitly describe processes and test methods. In this presentation, the first efforts within the joint project PMD in creating a tensile test application ontology in accordance with the ISO standard 6892-1:2019-11 are shown. Especially, the path of ontology development to be pursued based on standards was focused. Furthermore, the presentation includes a live demonstration of queries possibly performed to query data that was uploaded in the PMD triple store.
As the well-known damage mechanisms slow crack growth (SCG) and environmental stress cracking (ESC) are the major causes for possible failure of polyolefin-based materials, especially for PE-HD, they are highly relevant and need to be considered thoroughly. Furthermore, due to slight but perceptible differences in damaging effect, a differentiation between SCG and ESC is expedient. SCG appears in “inert” or “neutral” media without a decisive influence of the surrounding medium whereas ESC occurs in “active” media, which influence the failure behavior and time to failure crucially.
To characterize the inherent resistance of the material against those damage mechanisms, the well-established Full-Notch Creep Test (FNCT) is used. In this study, the FNCT – usually applied according to ISO 16770 [3] using a few universal model liquid media and mainly for pipe materials – is extended by investigations with appropriate parameters of selected relevant PE-HD container materials also in real media, such as the topical fuels diesel and biodiesel. The investigations were performed using a novel FNCT-device with 12 individual sub-stations, each equipped with individual electronic stress and temperature control and continuous online monitoring of the specimen elongation.
Especially, mechanical stress and temperature were varied systematically during FNCT and time to failure values, time-dependent elongation data as well as detailed fracture surface analysis by laser scanning microscopy (LSM) were combined for the first time (Fig. 1). Particularly, the fracture surface analysis provides a sound basis to characterize failure behavior, mainly regarding the balance between brittle crack propagation and ductile deformation. Therefore, fracture surface analysis is an essential tool for a decent assessment of SCG and ESC by FNCT measurements.
During their lifetime, polymer components subjected to mechanical loads and environmental influences show a loss of their mechanical properties required for their specific applications. In this respect, the craze-crack damage mechanism slow crack growth (SCG) is relevant for PE-HD components used in high-performance applications such as pipes and containers for the storage and transport of dangerous goods. SCG is considered to be the major failure mechanism in polyolefins and it typically occurs suddenly and unexpectedly. Due to the fields of application, SCG is a safety relevant issue. To test for the resistance of PE-HD pipe and container materials against SCG, the full-notch creep test (FNCT) is widely applied in Europe. In this study, SCG phenomena in PE-HD are investigated in detail based on an improved FNCT, especially including the consideration of the influence of environmental liquids effecting the damage mechanism. Using an enhanced fracture surface and a crack propagation analysis with imaging techniques such as light microscopy (LM), laser scanning microscopy (LSM), X-ray computed tomography (CT-scan) and scanning electron microscopy (SEM), detailed data concerning SCG are obtained.
The combined application of FNCT and such imaging techniques is explicitly advantageous and recommended to gain important information on damage occurring to PE-HD induced by mechanical stress and the influence of environmental liquids, which is essential within the Fourth Industry Revolution.
The full-notch creep test (FNCT) is a common method to evaluate the environmental stress cracking (ESC) behavior of high-density polyethylene (PE-HD) container materials . The test procedure as specified in ISO 16770 provides a comparative measure of the resistance against ESC using the time to failure of specimens mechanically loaded in a well-defined liquid environment. Since the craze-crack damage mechanism underlying the ESC process is associated with brittle failure, the occurrence of globally brittle fracture surfaces is a prerequisite to consider an FNCT measurement as representative for ESC . Therefore, an optical evaluation of FNCT fracture surfaces concerning their brittleness is essential. Due to the experimental setup, an inevitable increase of the true mechanical stress and the associated appearance of small ductile parts on fracture surfaces is induced in any case. Hence, an FNCT experiment is considered as 'valid', if the corresponding fracture surface is predominantly brittle . Based on laser scanning microscopy (LSM) height data of FNCT fracture surfaces , a universal and easy-to-use phenomenological criterion was developed to assess the validity of distinct FNCT experiments. This criterion is supposed to facilitate a quick evaluation of FNCT results in practical routine testing.
Environmental Stress Cracking (ESC) and Slow Crack Growth (SCG) of PE-HD induced by external fluids
(2020)
High-density polyethylene (PE-HD) is widely used as a packaging material. Typical applications are pipes and containers for storage and transport of dangerous goods. For these applications, the understanding of the craze-crack damage mechanisms slow crack growth (SCG) and environmental stress cracking (ESC) is of importance. Since these mechanisms are considered to be the major causes of failure, their understanding is essential for inspection and release of those materials.
A well-established test method for the assessment of these damage mechanisms is the full-notch creep test (FNCT). It is used in this study for a detailed investigation of crack propagation phenomena in PE-HD container materials under the influence of different fluids such as air, water and aqueous detergent solutions (Arkopal N 100) as well as biodiesel and diesel. Based on the results of the FNCT, a classification scheme of different fluids is proposed, which allows for an assignment of the respective damage mechanisms. Hereby, it is differentiated between (i) inert, (ii) purely surface-active and (iii) additionally sorptive, bulk-active fluids with respect to SCG. If the test fluid changes the intrinsic properties (at the surface or in the bulk), the damage mechanism is addressed to ESC behavior.
In FNCT investigations, stress, temperature and specimen geometry were varied systematically. In addition to the time to failure as common measure for the resistance of a PE-HD type against crack propagation, specimen elongation was considered in detail.
Several imaging techniques were applied for fracture surface analysis of specimens tested in FNCT to gain novel information on SCG and ESC behavior. From height profiles obtained by laser scanning microscopy (LSM) and information on surface structures from scanning electron microscopy (SEM), indicators for the differentiation of the crack propagation mechanisms could be derived. Based on the LSM data, an algorithm for the distinction between ductile shear deformation and brittle crack growth as dominating failure mechanism was developed. Imaging techniques were also used for determination of crack propagation rates, which were related to time-resolved FNCT elongation data. From the time-resolved determination of crack lengths of partly damaged FNCT specimens, an increasing length of craze zone with a progressively propagating crack was revealed for the first time. This relation of crack and craze zones was specified by fracture mechanical considerations.
Data analysis methods play an important role in both the experimental and simulation-based digital description of materials but have so far been poorly structured. The platform Material Digital (PMD) should contribute to a standardized description of data processing methods in materials research. The goal is the quality assurance of the processes and the output data, the acquisition and definition of their accuracy as well as the interoperability between applications.
Therefore, application ontologies are created to explicitly describe processes and test methods. In this presentation, the first efforts in creating a tensile test application ontology in accordance with the ISO standard 6892-1:2019-11 are shown. Especially, the path of ontology development to be pursued based on standards was focused.
The efforts taken within the project ‘platform MaterialDigital’ (PMD, materialdigital.de) to store FAIR data in accordance with a standard-compliant ontological representation (‘application ontology’) of a tensile test of metals at room temperature (ISO 6892-1:2019-11) will be presented. This includes the path from developing an ontology in accordance with the respective standard, converting ordinary data obtained from standard tests into the interoperable RDF format, up to connecting the ontology and data. The semantic connection of the ontology and data leads to interoperability and an enhanced ability of querying. For further reusability of data and knowledge semantically stored, the PMD core ontology (PMDco) was developed, which is a mid-level ontology in the field of MSE. The semantic connection of the tensile test application ontology to the PMDco is also presented. Moreover, Ontopanel, a tool for domain experts facilitating visual ontology development and mapping for FAIR data sharing in MSE, is introduced briefly.
This is an interactive workshop of the Plattform MaterialDigital (PMD) on Semantic Web technologies (SWT) where we delve into the world of ontology development and data structuring in the field of materials science and engineering (MSE). This workshop is designed to equip participants with essential skills in categorizing classes within ontologies, with a special emphasis on the PMD Core Ontology (PMDco). Discover the immense value of ontologies for MSE data reproducibility and reuse and harness the power of PMDco to foster your data management practices.
In this workshop, you will explore the intricacies of class categorization when developing ontologies in the MSE domain. Through interactive discussions and hands-on exercises, you will learn effective techniques for structuring and organizing ontologies to enhance data retrieval and analysis. You will gain valuable insights into best practices and considerations for class categorization, aiming at optimal data organization and management within your MSE projects.
One of the highlights of this workshop is the introduction to PMDco, a mid-level ontology in the field of MSE developed community-driven in the frame of the project PMD. Learn about PMDco, its underlying concepts, and its application in detail. Discover how PMDco provides a comprehensive framework for MSE data representation, enabling seamless integration and interoperability across different systems and platforms. In addition to exploring PMDco, this workshop will illustrate the benefits of data interoperability and SWT with respect to leveraging the full potential of MSE data.
Knowledge representation in the materials science and engineering (MSE) domain is a vast and multi-faceted challenge: Overlap, ambiguity, and inconsistency in terminology are common. Invariant and variant knowledge are difficult to align cross-domain. Generic top-level semantic terminology often is too abstract, while MSE domain terminology often is too specific.
In this poster presentation, an approach how to maintain a comprehensive and intuitive MSE-centric terminology composing a mid-level ontology–the PMD core ontology (PMDco)–via MSE community-based curation procedures is shown.
The PMDco is designed in direct support of the FAIR principles to address immediate needs of the global experts community and their requirements. The illustrated findings show how the PMDco bridges semantic gaps between high-level, MSE-specific, and other science domain semantics, how the PMDco lowers development and integration thresholds, and how to fuel it from real-world data sources ranging from manually conducted experiments and simulations as well as continuously automated industrial applications.
This is the stable version of the full-notch creep test ontology (OntoFNCT) that ontologically represents the full-notch creep test. OntoFNCT has been developed in accordance with the corresponding test standard ISO 16770:2019-09 Plastics - Determination of environmental stress cracking (ESC) of polyethylene - Full-notch creep test (FNCT).
The OntoFNCT provides conceptualizations that are supposed to be valid for the description of full-notch creep tests and associated data in accordance with the corresponding test standard. By using OntoFNCT for storing full-notch creep test data, all data will be well structured and based on a common vocabulary agreed on by an expert group (generation of FAIR data) which is meant to lead to enhanced data interoperability. This comprises several data categories such as primary data, secondary data and metadata. Data will be human and machine readable. The usage of OntoFNCT facilitates data retrieval and downstream usage. Due to a close connection to the mid-level PMD core ontology (PMDco), the interoperability of full-notch creep test data is enhanced and querying in combination with other aspects and data within the broad field of materials science and engineering (MSE) is facilitated.
The class structure of OntoFNCT forms a comprehensible and semantic layer for unified storage of data generated in a full-notch creep test including the possibility to record data from analysis and re-evaluation. Furthermore, extensive metadata allows to assess data quality and reliability. Following the open world assumption, object properties are deliberately low restrictive and sparse.
Knowledge representation in the materials science and engineering (MSE) domain is a vast and multi-faceted challenge: Overlap, ambiguity, and inconsistency in terminology are common. Invariant and variant knowledge are difficult to align cross-domain. Generic top-level semantic terminology often is too abstract, while MSE domain terminology often is too specific.
In this presentation, an approach how to maintain a comprehensive and intuitive MSE-centric terminology composing a mid-level ontology–the PMD core ontology (PMDco)–via MSE community-based curation procedures is shown.
The PMDco is designed in direct support of the FAIR principles to address immediate needs of the global experts community and their requirements. The illustrated findings show how the PMDco bridges semantic gaps between high-level, MSE-specific, and other science domain semantics, how the PMDco lowers development and integration thresholds, and how to fuel it from real-world data sources ranging from manually conducted experiments and simulations as well as continuously automated industrial applications.
Tensile Test Ontology (TTO)
(2023)
This is the stable version 2.0.1 of the PMD ontology module of the tensile test (Tensile Test Ontology - TTO) as developed on the basis of the 2019 standard ISO 6892-1: Metallic materials - Tensile Testing - Part 1: Method of test at room temperature.
The TTO was developed in the frame of the PMD project. The TTO provides conceptualizations valid for the description of tensile test and corresponding data in accordance with the respective standard. By using TTO for storing tensile test data, all data will be well structured and based on a common vocabulary agreed on by an expert group (generation of FAIR data) which will lead to enhanced data interoperability. This comprises several data categories such as primary data, secondary data and metadata. Data will be human and machine readable. The usage of TTO facilitates data retrieval and downstream usage. Due to a close connection to the mid-level PMD core ontology (PMDco), the interoperability of tensile test data is enhanced and data querying in combination with other aspects and data within the broad field of material science and engineering (MSE) is facilitated.
The TTO class structure forms a comprehensible and semantic layer for unified storage of data generated in a tensile test including the possibility to record data from analysis, re-evaluation and re-use. Furthermore, extensive metadata allows to assess data quality and reproduce experiments. Following the open world assumption, object properties are deliberately low restrictive and sparse.
Following the new paradigm of materials development, design and optimization, the digitalization of materials and processes is the main goal which imposes a huge challenge. In this respect, the quality assurance of processes and output data as well as the interoperability between applications following FAIR (findability, accessibility, interoperability, reusability) principles are to be ensured. This includes storage, processing and querying of data in a preferably standardized form, also addressing the incorporation of standardization bodies. To meet the challenge to contextualize material data in a way that is consistent with all stakeholders, all necessary information on the condition of the material including production and application-related changes have to be made available via a uniform, machine-readable description. For this purpose, ontologies are to be used since they allow for machine-understandable knowledge representations and semantic conceptualizations that are needed for data management and the digitalization in the field of materials science.
With respect to this currently ever-growing topic of integration and reuse of data and knowledge from synthesis, production and characterization of materials, this presentation shows the efforts taken within the project Platform MaterialDigital (PMD, materialdigital.de) to store tensile test data in accordance with a standard-compliant ontological representation. The includes the path from developing an ontology in accordance with the respective standard, converting ordinary and arbitrarily selected data gained from standard tests into the interoperable RDF format, up to connecting the ontology and data, respectively. Finally, such data can be queried from a triple store.
In the field of material science and engineering (MSE), most mechanical test methods are standardized which serves as a valid basis for ontology development. Therefore, the well-known tensile test of metals at room temperature (DIN EN ISO standard 6892-1:2019-11) was selected to be considered as one of the first use cases in PMD. This consideration within the PMD features both, the ontological representation of such a tensile test in accordance with the standard as well as exemplary data generation. The semantic connection of the ontology and data leads to interoperability and an enhanced ability of querying.
Following the new paradigm of materials development, design, and optimization, digitalization is the main goal in materials sciences and engineering (MSE) which imposes a huge challenge. In this respect, the quality assurance of processes and output data as well as the interoperability between applications following FAIR principles are to be ensured. For storage, processing, and querying of data in contextualized form, Semantic Web technologies (SWT) are used since they allow for machine-actionable and human-readable knowledge representations needed for data management, retrieval, and (re)use.
The project ‘platform MaterialDigital’ (PMD, https://materialdigital.de) aims to bring together and support interested parties from both industrial and academic sectors in a sustainable manner in solving digitalization tasks and implementing digital solutions. Therefore, the establishment of a virtual material data space and the systematization of the handling of hierarchical, process-dependent material data are focused. Core points to be dealt with are the development of agreements on data structures and interfaces implemented in distinct software tools and to offer users specific support in their projects. Furthermore, the platform contributes to a standardized description of data processing methods in materials research. In this respect, selected MSE methods are semantically represented which are supposed to serve as best practice examples with respect to knowledge representation and the creation of knowledge graphs used for material data.
Accordingly, this presentation shows the efforts taken within the PMD project towards the digitalization in MSE such as the development of the mid-level PMD core ontology (PMDco, https://github.com/materialdigital/core-ontology). Furthermore, selected results of a PMD partner project use case addressing data and knowledge management from synthesis, production, and characterization of materials are shown.
Morphologies of Fresnoite surface crystals of BT0.75S glass under different atmospheric conditions
(2019)
Fresnoite glass-ceramics are characterized by piezoelectric, pyroelectric and non-linear optical properties. These properties can be adjusted by orienting the fresnoite crystals during crystallization. Crystallization begins at the surface. The first surface crystals are not oriented perpendicular and, therfore, produce a surface layer that has not the intended properties. To overcome this issue, the formation of fresnoite surface crystals at different atmospheric conditions was studied.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: Corrosion of pipeline steel, pipeline network design and related transport costs, alteration of well bore cements, pressure evelopment and rock integrity, geochemical reactions, and petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for eachindividual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv)impurity combinations to be avoided.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: Corrosion of pipeline steel, pipeline network design and related transport costs, alteration of well bore cements, pressure development and rock integrity, geochemical reactions, and petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.
The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on:
• corrosion of pipeline steel,
• pipeline network design and related transport costs,
• alteration of well bore cements,
• pressure development and rock integrity,
• geochemical reactions, and
• petrophysical and geomechanical rock properties.
All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein.
The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.
Depending on the CO2 generating and the capture process as well as on consecutive purification steps applied, CO2 streams from different emitters may differ in their composition. When CO2 streams with different compositions are fed into a larger pipeline network, there are several aspects that must be considered: i) chemical reactions, such as acid formation, may occur within the joint CO2 stream; ii) there may be a variation of mass flow rate and CO2 stream composition within the pipeline network if the feed-in behavior of different CO2 sources changes with time. Potential impacts of changing CO2 stream compositions and mass flow rates in CCS cluster systems were investigated in the collaborative project "CLUSTER" (see also www.bgr.bund.de/CLUSTER). In this presentation, we focus on the experimental investigations of formation and condensation of strong acids and their impacts on the corrosion of pipeline steels. When SO2, NO2, O2 and H2O are present simultaneously in CO2 streams chemical cross-reactions may occur leading to the formation of strong acids such as sulfuric and nitric acid. To prevent this acid formation the concentration of at least one of these four impurities must be kept very low (e.g., Rütters et al., 2016). At temperatures below the acid dew point temperature, acids will condense, e.g., on pipeline steel surfaces. In turn, these acid condensates may trigger steel corrosion. To better understand the process of acid formation and condensation and its implications for steel corrosion, exposure tests were performed on pipeline steel X70 in dense CO2 with varying SO2, NO2 and O2 concentration under high pressure and at 278 K in an observable autoclave, in which water was added as droplets or as vapor. Further, electrochemical tests were carried out with X70 specimens immersed in 500 mL CO2-saturated synthetic condensate solution or in droplets of the same solution on the specimen’s surface. Depending on impurity concentrations in the CO2 streams, condensates consisting of different relative amounts of nitric and sulfuric acid were formed. In condensates containing both nitric and sulfuric acid, corrosion rates were higher than the sum of those of the individual acids. In addition, corrosion products and forms depended on the condensate composition. Investigations of water droplets on steel surfaces in impurity-containing dense-phase CO2 revealed the diffusion of SO2 and NO2, followed by cross-reactions forming corresponding acids. An increase in droplet size (from 1 to 5 µl) lead to higher corrosion rates. However, in comparison to measurements in bulk solution, corrosion reactions in droplets resulted in thick, high-resistance corrosion products and observed droplet corrosion rates were significantly lower. In addition, the possibility of acid droplet formation and growth in impure liquid CO2 is influenced by the wetting behavior of the acid droplet on the steel surface. Thus, the contact angle between a water droplet and the surface steel specimens in a CO2 atmosphere was investigated in a high pressure view cell following the sessile drop method. The contact angle wasand found to be larger at higher CO2 pressures (studied from 5 to 20 MPa) and at higher temperatures (e.g. 278 K to 333 K). Further, measured contact angles were larger on rough than on smooth metal surfaces. In addition, acid formation reduced the contact angle, i.e. lead to better wetting, thereby stimulating condensation that was followed by a corrosion process. These detailed insights on the complex interplay of acid formation, condensation, wetting behavior and corrosion allow a better assessment of material suitability for pipeline transportation of impure CO2 streams
Due to their excellent combination of ductility, strength and corrosive resistance, austenitic stainless steels (ASS) are widely used in many industrial applications. Thus, these steel grades can be found as structural components in the (petro-)chemical industry, in offshore applications and more recent for storage and transport of hydrogen fuel. Steels employed for these applications are exposed to aggressive environments and hydrogen containing media. The ingress and accumulation of hydrogen into the microstructure is commonly observed during service leading to a phenomenon called “hydrogen embrittlement”. A loss in ductility and strength, the formation of cracks and phase transformations are typical features of this hydrogen-induced degradation of mechanical properties.
Although, great efforts are made to understanding hydrogen embrittlement, there is an ongoing debate of the underlying mechanisms. This knowledge is crucial for the safe use and durability of components on the one side and the development of new materials on the other.
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was proven to be a powerful tool for depicting the distribution of the hydrogen isotope deuterium in the microstructure of austenitic and duplex steels. The combination with imaging techniques such as electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM), delivering structural and morphological information, creates a comprehensive picture of the hydrogen/deuterium-induced effects in the materials. All the gathered data is treated with principal component analysis (PCA) and data fusion to enhance the depth of information.
The mobility of hydrogen and deuterium in a steel microstructure is affected by external mechanical stress. To investigate the behaviour of deuterium in a strained microstructure, a new in situ experimental approach was developed. This gives the possibility of analysing samples in the SIMS instrument simultaneously to four-point-bending-tests.
Specimens made from ASS AISI 304L were electrochemically charged with deuterium instead of hydrogen. This necessity stems from the difficulty to separate between artificially charged hydrogen and hydrogen existing in the pristine material or adsorbed from the rest gas in the analysis chamber. Nonetheless, similar diffusion, permeation and solubility data allow to draw qualitative conclusions from the experiments, which are relevant for the application addressed.
The reduction of harmful emissions to the environment is one of the most urgent challenges of our time. To achieve this goal, it is inevitable to shift from using fossil fuels to renewable energy sources. Within this transition, hydrogen can play a key role serving as fuel in transportation and as means for energy storage.
The storage and transport of hydrogen using austenitic stainless steels as the infrastructure, as well as the use of these grades in hydrogen containing aggressive environments, remains problematic. The degradation of the mechanical properties and the possibility of phase transformation by ingress and accumulation of hydrogen are the main drawbacks. Advanced studies of the behaviour of hydrogen in austenite is necessary to fully understand the occurring damage processes. This knowledge is crucial for the safe use of components in industry and transportation facilities of hydrogen.
A powerful tool for depicting the distribution of hydrogen in steels, with high accuracy and resolution, is time-of-flight secondary ion mass spectrometry (ToF-SIMS). We here present a comprehensive research on the hydrogen degradation processes in AISI 304L based on electrochemical charging and subsequent ToF-SIMS experiments. To obtain furthermore information about the structural composition and cracking behaviour, electron-backscattered diffraction (EBSD) and scanning electron microscopy (SEM) were performed afterwards. All the gathered data was treated employing data fusion, thus creating a thorough portrait of hydrogen diffusion and its damaging effects in AISI 304L.
Specimens were charged with deuterium instead of hydrogen. This necessity stems from the difficulty to separate between artificially charged hydrogen and traces existing in the material or adsorbed from the rest gas in the analysis chamber. Similar diffusion and permeation behaviour, as well as solubility, allow nonetheless to draw onclusions from the experiments.
The employment of renewable energy resources, which are naturally intermittent, for electricity generation has altered the working conditions of conventional power plants from continuous (baseload) to cyclic or flexible operation. For a long time, 9-12% Cr ferritic-martensitic stainless steels have been widely used in power plants due to their favorable characteristics such as high creep strength at high temperatures and oxidation and corrosion resistance. The components of power plants are subjected to long term cyclic loadings including fatigue and creep-fatigue at high temperatures. As ferritic-martensitic steels are known to exhibit cyclic softening when subjected to such loading scenarios, it is crucial to study the material response in such conditions. Since it is impossible to test the material behavior exactly as the operation conditions of power plants, due to technical difficulties and cost issues, it is necessary to develop physically-based material models that can predict the material behavior in more realistic situations.
In recent years, many material models have been proposed to describe the behavior of 9-12% Cr ferritic-martensitic stainless steels, which follow phenomenological or physically-based approaches. Phenomenological models provide a stress-strain relation based on empirical observations although they usually lack physical background. To alleviate this drawback and to allow for more flexibility and wider ranges of strain-rate and temperature, physically-based models are suggested. In this approach, microstructural evolution, dislocation movement and/or kinetics of plastic deformation processes are included. The physically-based models allow for a better extrapolation from the experiment results to other operation conditions and their material constants can be interpreted physically. Compared to the former approach, the material behavior can be described more accurately and flexibly and the number of material constants is less in general. In the presented work, the existing micromechanical models developed for P92 steel are compared and extended to allow for new dislocation-based strengthening/cyclic mechanisms. Their performance is assessed in the light of mechanical test data from creep-fatigue and thermo-mechanical fatigue experiments and detailed characterizations of the microstructure evolution in the fatigued material.
The influence of prestraining on the aging response of an Al-Cu-Li alloy is investigated by preparation of different strain states (3 %, 4 %, 6 %) of the initial aging state. The Brinell hardness of the subsequently aged samples (up to 60 h aging time) was measured and it was found that the increasing dislocation concentration in the 3 different initial states leads to faster hardness increases and slightly higher maximum hardness.
The influence of heat treatment and creep loading on the microstructure of an Al-Cu-Li alloy was investigated. Especially the formation of different precipitates (T1 and Theta') were characterized and the microstructural changes under different ageing conditions (with and without external strain) were investigated to determine the effect od stress on the ageing process.
The influence of heat treatment and creep loading on the microstructure of an Al-Cu-Li alloy was investigated. Especially the formation of different precipitates (T1 and Theta') were characterized and the microstructural changes under different ageing conditions (with and without external strain) were investigated to determine the effect od stress on the ageing process.
This dataset consists of indentation data measured with a conospherical tip in a Hysitron-Bruker TI980 Nanoindenter on the surface of a <100> Silicon wafer and a polished cross-sectional cut of a Zr65Cu25Al10 bulk metallic glass.
It is associated with the following publication:
Birte Riechers, Catherine Ott, Saurabh Mohan Das, Christian H. Liebscher, Konrad Samwer, Peter M. Derlet and Robert Maass "On the elastic microstructure of bulk metallic glasses" Materials and Design xxx, (2023) 111929. https://doi.org/10.1016/j.matdes.2023.111929
All experimental information can be found in this paper and in the accompanying supplementary information.
This electronic version of the data was published on the "Zenodo Data repository" found at http://zenodo.org/deposit in the community "Bundesanstalt fuer Materialforschung und -pruefung (BAM)".
The authors have copyright to these data. You are welcome to use the data for further analysis, but are requested to cite the original publication whenever use is made of the data in publications, presentations, etc.
Any questions regarding the data can be addressed to birte.riechers@bam.de who would also appreciate a note if you find the data useful.
HEAs represent a relatively new class of materials. The the alloy concept is fundamentally different from the most conventional materials and alloys that are used today. Recently, the focus of HEA designs is more application-based. For that purpose, the elements of interest are carefully selected and multiple phases as well as micro-structures are deliberately adjusted. Currently, only limited attention has been paid to weldability of HEA. This encompasses possible effects on metallurgy and its influence on the desired properties. It remains open if welding causes e.g. considerable number of intermetallic phases or segregations and their effect on weld joint properties. For that reason, the scope of this study is to summarize already available studies on welding of HEAs with respect to the HEA-type, the applied welding process and its influence on the weld joint properties.
The permeation of hydrogen gas was studied in meta-aluminous (tectosilicate) glass powders of Li2O×Al2O3×SiO2 (LAS), Na2O×Al2O3×SiO2 (NAS) and MgO×Al2O3×SiO2 (MAS) systems by pressure loading and vacuum extraction in the temperatures range 210–310 °C. With this method, both the solubility S and the diffusivity D were determined, while the permeability was given by the product SD. For all glasses, S was found to decrease with temperature, while D increased. Since the activation energy of diffusion of H2 molecules exceeded that of dissolution, permeation increased slightly with temperature. When extrapolated to standard conditions (25 °C), the permeability of tectosilicate glasses was found to be only 10-22–10-24 mol H2 (m s Pa)-1, which is 8–10 magnitudes lower than most polymers. Thin glass liners of these compositions are expected to be the most effective barrier for tanks of pressurised hydrogen.
Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. For silicate glasses we found a good correlation between the calculated surface energy of crystal faces and oriented surface nucleation. Surface energies were estimated assuming that crystal surfaces resemble minimum energy crack paths along the given crystal plane. This concept was successfully applied by Rouxel in calculating fracture surface energies of glasses. Several oriented nucleation phenomena can be herby explained assuming that high energy crystal surfaces tend to be wetted by the melt. This would minimize the total interfacial energy of the nucleus. Furthermore, we will discuss the evolution of the microstructure and its effect on the preferred crystal orientation.
Up to now, the mechanisms of surface nucleation and surface-induced texture formation are far from being understood. Corresponding phenomena are discussed hypothetically or even controversial, and related studies are restricted to very few glasses. In this talk the state of the art on mechanisms of surface nucleation are summarized. On one hand, mechanical damaged surfaces show high nucleation activity, at which the nucleation occurs at convex tips and edges preferentially. On the other hand, solid foreign particles are dominant nucleation sites at low damaged surfaces. They enable nucleation at temperatures even far above Tg. The nucleation activity of the particles is substantially controlled by their thermal and chemical durability. But no systematic studies on initially oriented crystal growth or nucleation from defined active nucleation sites have been pursued, so far. Therefore, the main objective of a just started project is to advance the basic understanding of the mechanisms of surface-induced microstructure formation in glass ceramics. We shall answer the question whether preferred orientation of surface crystals is the result of oriented nucleation or caused by other orientation selection mechanisms acting during early crystal growth. In both cases, crystal orientation may be caused by the orientation of the glass surface itself or the anisotropy and orientation of active surface nucleation defects. As a first attempt we focused on possible reorientation of separately growing surface crystals during early crystal growth. First results show clear evidence that separately growing crystals can reorient themselves as they are going to impinge each other.
Glass powders are promising candidates for manufacturing a broad diversity of sintered materials like sintered glass-ceramics, glass matrix composites, glass bonded ceramics or pastes. Powder processing, however, can substantially affect sinterability, e.g. by promoting surface crystallization. On the other hand, densification can be hindered by gas bubble formation for slow crystallizing glass powders. Against this background, we studied sintering and foaming of silicate glass powders with different crystallization tendency for wet milling and dry milling in air, Ar, N2, and CO2 by means of heating microscopy, DTA, Vacuum Hot Extraction (VHE), SEM, IR spectroscopy, XPS, and ToF-SIMS. In any case, foaming activity increased significantly with progressive milling. For moderately milled glass powders, subsequent storage in air could also promote foaming. Contrarily, foaming could be substantially reduced by milling in water and 10 wt% HCl. Although all powder compacts were uniaxially pressed and sintered in air, foaming was significantly affected by different milling atmosphere and was found most pronounced for milling in CO2 atmosphere. Conformingly, VHE studies revealed that foaming is mainly driven by carbonaceous species, even for powders milled in other gases. Current results of this study thus indicate that foaming is caused by carbonaceous species trapped on the glass powder surface.
Up to now, oriented surface crystallization phenomena are discussed controversially, and related studies are restricted to few glasses. The vast majority of previous work does not consider possible effects of surface preparation and surrounding atmosphere. Moreover, very few observations of surface crystal orientation were made on separately grown crystals.
The aim of our project is to advance the basic understanding of oriented surface crystallization, e.g. whether preferred orientation of surface crystals results from oriented nucleation or reorientation mechanisms during early crystal growth. In both cases, crystal orientation may reflect the orientation of the glass surface or that of anisotropic active surface nucleation sites. Therefore, we focus on orientation of surface crystals separately growing under controlled conditions.
First results on diopside (MgCaSi2O6) and walstromite (BaCa2Si3O9) crystals growing from 18BaO·22CaO·60SiO2 and MgO·CaO·2SiO2 glass surfaces, respectively, indicate that different orientation mechanisms may occur.
Neighbored walstromite crystals were found to gradually reorient themselves when they are going to impinge each other during stepwise isothermal treatments (log η = 4,5 Pa*s) of polished glass samples. Nevertheless, no preferred crystal orientation was evident for separate crystals.
For diopside crystals growing from polished glass surfaces (1 μm diamond lapping foil), strong preferred orientation was observed for 3.5 to 85 min annealing at 850 °C. Electron Backscatter Diffraction (EBSD) studies showed that the c-axis of surface crystals is oriented parallel to the glass surface and that separated diopside crystals as small as 600 nm are already oriented. Studies on glass surfaces, polished with diamond lapping foils starting from 16 μm down to 1 μm grain, revealed that crystal orientation may scatter arround this preferential orientation and that this scatter progressively decreases with decreasing polishing grain size.