5 Werkstofftechnik
Filtern
Dokumenttyp
- Vortrag (121)
- Zeitschriftenartikel (71)
- Beitrag zu einem Tagungsband (24)
- Forschungsdatensatz (21)
- Posterpräsentation (20)
- Buchkapitel (7)
- Dissertation (4)
- Forschungsbericht (4)
- Sammelband (Herausgeberschaft für den kompletten Band) (3)
- Monografie (1)
Sprache
- Englisch (227)
- Deutsch (49)
- Französisch (1)
Schlagworte
- Ontology (33)
- Creep (27)
- Microstructure (23)
- Additive manufacturing (21)
- LCF (16)
- Additive Manufacturing (14)
- Degradation (13)
- Fatigue (13)
- Ti-6Al-4V (13)
- Aluminium (11)
- Alloy 2618A (10)
- Coarsening (10)
- FAIR (10)
- 316L (9)
- Aging (9)
- EN AW-2618A (9)
- Low Cycle Fatigue (9)
- Transmission electron microscopy (9)
- Crystal plasticity (8)
- Digitalization (8)
- Nickel-base superalloys (8)
- Ontologie (8)
- Residual stress (8)
- S-phase (8)
- Semantic Web Technologies (8)
- AGIL (7)
- AISI 316L (7)
- Additive Fertigung (7)
- Aluminium alloy (7)
- Anisotropy (7)
- Kriechen (7)
- Mechanical testing (7)
- Plattform MaterialDigital (7)
- Semantic Interoperability (7)
- Thermomechanical fatigue (7)
- Zugversuch (7)
- Data Interoperability (6)
- Knowledge Representation (6)
- Mikrostruktur (6)
- P92 (6)
- TMF (6)
- Computed Tomography (5)
- Crack growth (5)
- Damage (5)
- Dark-field transmission electron microscopy (DFTEM) (5)
- Data mapping (5)
- Digitalisierung (5)
- FAIR data (5)
- FAIR data management (5)
- Fe-Al alloys (5)
- HIP (5)
- Intermetallics (5)
- Iron aluminides (5)
- Knowledge graph and ontologies (5)
- Laser powder bed fusion (5)
- PMD Core Ontology (5)
- Reference data (5)
- Shear modulus (5)
- Stress relaxation (5)
- Tensile Test (5)
- Tensile testing (5)
- Wissensrepräsentation (5)
- Young's modulus (5)
- Aluminum alloys (4)
- Brinell hardness (4)
- Creep-fatigue (4)
- Data Fusion (4)
- EBSD (4)
- Elastic modulus (4)
- Electron microscopy (4)
- Fatigue crack growth (4)
- Laser Powder Bed Fusion (4)
- Microstrucrue Design (4)
- Ni-Resist (4)
- Normung (4)
- Phase-field simulation (4)
- Plattform Material Digital (4)
- Scale-bridging (4)
- Schädigung (4)
- Superalloy (4)
- Tensile Test Ontology (4)
- Tensile test (4)
- Virtual experiments (4)
- Crack (3)
- Crack propagation (3)
- Crack tip opening displacement (3)
- Creep behavior (3)
- Creep data (3)
- Dark-field transmission electron microscopy (3)
- Diffraction (3)
- Digtial Representation (3)
- Electronic Lab Notebook (3)
- Ferritic-martensitic steels (3)
- Fractography (3)
- Hardness (3)
- Heat treatment (3)
- High temperature mechanical properties (3)
- IN 718 (3)
- Interoperability (3)
- Knowledge graph (3)
- Lebensdauer (3)
- Low cycle fatigue (3)
- Mechanical behavior (3)
- Mechanische Eigenschaften (3)
- Metadata schema (3)
- Microstructure evolution (3)
- Ontologies (3)
- PBF-LB/M/316L (3)
- PMDco (3)
- Phase-field (3)
- Precipitation (3)
- Referenzdaten (3)
- Reproducibility (3)
- Research Data Management (3)
- S-Phase (3)
- Semantic Data (3)
- Semantic Web (3)
- Single-crystals (3)
- Superalloys (3)
- Superlegierung (3)
- Syngle Crystal alloy (3)
- Tempered Martensite Ferritic Steels (3)
- Tempered martensite-ferritic steel (3)
- Tensile data (3)
- Thermo-Mechanical Fatigue (3)
- Al-Cu-Li alloys (2)
- Alterung (2)
- Aluminium Alloy (2)
- Aluminum (2)
- Aluminum alloy (2)
- CALPHAD (2)
- CT (2)
- Casting (2)
- Chemo-mechanical coupling (2)
- Computed tomography (2)
- Concrete (2)
- Continnum damage model (2)
- Copper (2)
- Copper alloys (2)
- Creep-Fatigue (2)
- Cyclic softening (2)
- Data Management (2)
- Data Structures (2)
- Data management (2)
- Dataset (2)
- Density-based Thermodynamics (2)
- Density-based model (2)
- Densty-based Thermodynamics (2)
- Diffraction Elastic Constants (2)
- Diffusion (2)
- Digital material representation (2)
- Digital representation (2)
- Digitization (2)
- Dislocation (2)
- Dislocations (2)
- Elasticity (2)
- Electron Backscatter Diffraction (2)
- Electron backscatter diffraction (2)
- Environmentally assisted cracking (2)
- FAIR Data Management (2)
- Fatigue performance (2)
- Fatigue testing (2)
- Finite element analysis (2)
- Fracture mechanics (2)
- Glass forming (2)
- High Cycle Fatigue (2)
- High Temperature Testing (2)
- Joined nickel-based alloys (2)
- Kleinprobenprüfung (2)
- Knowledge Graph (2)
- Laser Powder Bed fusion (2)
- Long-term behavior (2)
- Mass transport (2)
- Material digital (2)
- Materials science (2)
- Metal seal (2)
- Micromechanical model (2)
- Microstructure-property-correlation (2)
- Multiaxial deformation (2)
- NFDI (2)
- Neutron diffraction (2)
- Nickel-base alloy (2)
- Notches (2)
- Ontologien (2)
- Ontology development (2)
- Ostwald ripening (2)
- PMD (2)
- Parametric modeling (2)
- Plastic deformation (2)
- Polymer (2)
- Probengrößeneffekt (2)
- Rapid solidification (2)
- Residual Stress (2)
- S355 steel sheet (2)
- Semantic Representation (2)
- Semantic web (2)
- Semantisches Web (2)
- Simulation (2)
- Simulation of concrete (2)
- Single-Crystal (2)
- Standard (2)
- Standardisierung (2)
- Standardization (2)
- Structural steel (2)
- Superconducting magnet (2)
- Symmetric dwell periods (2)
- TEM (2)
- Tensile Properties (2)
- Thermodynamics (2)
- Ti64 (2)
- TiAl5V4 (2)
- Titan (2)
- Titanium (2)
- Under cyclic loading (2)
- Vickers hardness (2)
- Viscoplasticity (2)
- Wall thickness (2)
- Zugeigenschaften (2)
- 316L stainless steel (1)
- 3D-finite element modeling (1)
- 9-12% Cr ferritic-martensitic steels (1)
- 9-12%Cr steel (1)
- 9–12%Cr steel (1)
- AM (1)
- Abgasturbolader Heißteile (1)
- Accelerated integration scheme (1)
- Accelerated temporal integration (1)
- Accessible (1)
- Age hardening (1)
- Ageing (1)
- Al alloys (1)
- Al-Cu alloy (1)
- Al-Cu-Li-alloy (1)
- Al-Li alloys (1)
- Al2CuMg (1)
- Allgemeine Grundlagen (1)
- Alloy 2818A (1)
- Alloy design (1)
- Alloy microstructure (1)
- Aluminiumlegierung (1)
- Aluminum Alloy Aging (1)
- Anwendungen (1)
- Atomistic simulations (1)
- Aufbau von Festkörpern (1)
- Austenite-to-martensite phase transformation (1)
- Austenitic cast iron (1)
- Austenitischer Stahl (1)
- Automatable digital approach (1)
- Automated finite element analysis (1)
- Automated image analysis (1)
- Automation (1)
- Automatische Finite Element Simulation (1)
- Beanspruchung (1)
- Bitter technique (1)
- Bruch (1)
- CKAN (1)
- CMSX4 (1)
- Calibration (1)
- Carbon steel (1)
- Centrifugal casting (1)
- Centrifugal compressor wheel (1)
- Characterisation (1)
- Characterization (1)
- Charpy test (1)
- Chemische Analyse (1)
- Coefficient of thermal expansion (1)
- Complex borides (1)
- Compositionally complex alloys (1)
- Contact mechanics (1)
- Corrosion (1)
- Craze-crack mechanism (1)
- Creep behaviour (1)
- Creep mechanisms (1)
- Creep, Creep Rupture, and Stress Rupture (1)
- Creep-fatigue interaction (1)
- Crystal Defects (1)
- Crystal Plasticity Modelling (1)
- Crystalline defects (1)
- Cyclic loading (1)
- Cyclic oxidation (1)
- DED-L (1)
- DIN (1)
- Damage Behavior (1)
- Damage behavior (1)
- Data Exchange (1)
- Data Integration (1)
- Data Mapping (1)
- Data format (1)
- Data infrastructures (1)
- Data linking (1)
- Data pipeline concept (1)
- Data storage (1)
- Data structure (1)
- Datenfusion (1)
- Datenökosystem (1)
- Defects (1)
- Defects engineering (1)
- Defects phase diagram (1)
- Defects thermodynamics (1)
- Deformation (1)
- Deformation mechanisms (1)
- Demonstrators (1)
- Die casting (1)
- Differential scanning calorimetry (DSC) (1)
- Digital Transformation (1)
- Digital image correlation (1)
- Digital representations (1)
- Digital workflow (1)
- Digital workflows (1)
- Digitalizations (1)
- Domain Ontology Development (1)
- Dwell periods (1)
- Dwell times (1)
- Dwell-Fatigue (1)
- EN AW 2618A (1)
- EN AW 2618A a (1)
- Eigenschaften (1)
- Eigenspannung (1)
- Elastic constants (1)
- Elastic energy (1)
- Elctronic Lab Notebook (1)
- Electrical resistance (1)
- Electrochemical dressing (1)
- Electropolishing (1)
- Elektronisches Laborbuch (ELN) (1)
- Elektrotechnische Grundlagen (1)
- Energiewende (1)
- Energy transition (1)
- Entwicklung (1)
- Environment (1)
- Environmental Stress Cracking (1)
- Environmental stress cracking (ESC) (1)
- Ermüdung (1)
- Expanding cavity model (1)
- FAIR Data (1)
- FAIR data. (1)
- FAIR principles (1)
- FAIR research data management (1)
- FNCT (1)
- Fatigue crack propagation (1)
- Fatigue damage (1)
- Ferritic–martensitic steel (1)
- Finite elmenet simulation (1)
- Finite-Elemente-Methode (1)
- Fourier series (1)
- Full notch creep test (FNCT) (1)
- Full-Notch Creep Test (1)
- Full-notch creep test (1)
- Fullerite (1)
- GMR (1)
- GMR sensors (1)
- Gefügeuntersuchung (1)
- Gefügte Nickelbasislegierungen (1)
- General Chemistry (1)
- General Computer Science (1)
- General Engineering (1)
- General Materials Science (1)
- Glas (1)
- Gleichgewicht (1)
- Grade S960QL steel (1)
- Gradient-enhanced fatigue model (1)
- Grain Boundary Phase Diagram (1)
- Grain Boundary Segregation (1)
- Grain Boundary Spinodal (1)
- Grain boundaries (1)
- Grain boundary (1)
- Grain boundary phase diagram (1)
- Grain boundary thermodynamics (1)
- Graphic design (1)
- Grundlagen des Maschinenbaus (1)
- HCF (1)
- Hardness test (1)
- Heat Treatment (1)
- Hertzian cracks (1)
- High cycle fatigue (1)
- High entropy alloy (1)
- High entropy alloys (1)
- High-Entropy Alloys (1)
- High-entropy alloys (1)
- High-strength steel (1)
- High-temperature corrosion (1)
- Hochentropie-Legierung (1)
- Hochtemperatur (1)
- Hochtemperaturermüdung (1)
- Honing (1)
- Honing Stone (1)
- Hot isostatic pressing (HIP) (1)
- IN718 (1)
- In-Situ Testing (1)
- In-situ Process Monitoring (1)
- In-situ SEM micro shear deformation (1)
- In-situ diffraction (1)
- Inconel 718 (1)
- Incremental lifetime models (1)
- Indentation (1)
- Industrial and Manufacturing Engineering (1)
- Informationstechnische Grundlagen (1)
- Interfacial Spinodal (1)
- Interfacial anisotropy (1)
- Interfacial free energy (1)
- Intermetallische FeAl-Legierungen (1)
- Interoperable (1)
- Inverse ostwald ripening (1)
- Investment casting (1)
- Irregular topography (1)
- Isostatic hot pressing (HIP) (1)
- Kennwertermittlung (1)
- Keramik (1)
- Knowledge Graphs (1)
- Knowledge graphs (1)
- Knowledge representation (1)
- Korrosion (1)
- Kreislaufwirtschaft (1)
- Kriechermüdung (1)
- Kristallsystem (1)
- Kupfer (1)
- L-PBF 316L (1)
- LMD (1)
- Laser Poeder Bed Fusion (1)
- Laser Powder Bed Fusion (LPBF) (1)
- Laser Scanning Microscopy (1)
- Laser beam melting (LBM) (1)
- Laser powder-based directed energy deposition (1)
- Laser scanning microscopy (LSM) (1)
- Laser-Pulverbettschmelzen (1)
- Layering misalignment (1)
- Lebensdauervorhersage (1)
- Legierung mit komplexer Zusammensetzung (1)
- Life cycle (1)
- Lifetime prediction (1)
- Linked open data (1)
- Long-term aging (1)
- Low Cycle Fatigue (LCF) (1)
- Low carbon steel (1)
- Low strain (1)
- Low-Cycle Fatigue (LCF) (1)
- Low-Cycle-Fatigue (1)
- Low-cycle fatigue (1)
- Low-cycle fatigue. (1)
- Low-cycle-fatigue behaviour (1)
- Lötverbindung (1)
- Machine learning (1)
- Magnetic domain distribution (1)
- Magnetic domains (1)
- Magnetic stray field (1)
- Magnetic stray fields (1)
- Magnetische Domänen (1)
- Magnetoelastic effect (1)
- Magnetoelastischer Effekt (1)
- Magnetomechanical effect (1)
- Martensitic transformation (1)
- Mat-o-lab (1)
- Material Life Cycle (1)
- Material degradation (1)
- Material modeling (1)
- MaterialDigital (1)
- Materialcharakterisierung (1)
- Materialentwicklung (1)
- Materialkreislauf (1)
- Materialprüfung (1)
- Materials Chemistry (1)
- Materials Science (1)
- Materials Testing (1)
- Materials and Processes Data Reusability (1)
- Materials informatics (1)
- Materials science and engineering (1)
- Materials testing (1)
- Mathematisch-naturwissenschaftliche Grundlagen (1)
- Mechanical Engineering (1)
- Mechanical Properties (1)
- Mechanical anisotropy (1)
- Mechanics of Materials (1)
- Mechanisches Verhalten (1)
- Mechanistic Modelling (1)
- Mehrachsige Verformung (1)
- Mehrskalenmodell (1)
- Metal Magnetic Memory (1)
- Metal magnetic memory (1)
- Metall (1)
- Metals and Alloys (1)
- Micro computed tomography (1)
- Microstructural evolution (1)
- Microstructure analysis (1)
- Microstructure characterisation (1)
- Microstructure modification (1)
- Mid-Level Ontology for MSE (1)
- Mikro-Computertomographie (1)
- Mikrostrukturentwicklung (1)
- Mikrostrukturuntersuchung (1)
- Miniature specimens (1)
- Misfitting precipitate (1)
- Missing acknowledgment (1)
- Model (1)
- Modeling (1)
- Modell (1)
- Molecular dynamics (1)
- NFDI-MatWerk (1)
- NIST (1)
- Nanocrystalline alloys (1)
- Nanoindentation (1)
- NiTi (1)
- Nickel alloys (1)
- Nickel-base superalloy (1)
- Nimonic 75 (1)
- Non-destructive Materials (1)
- Non-destructive testing (1)
- Notch (1)
- Number density (1)
- Numerische Simulation (1)
- Ordering (1)
- Orowan Mechanism (1)
- Overaging (1)
- P92 steels (1)
- PE-HD (1)
- Phase Diagram (1)
- Phase field crystal (1)
- Phase field method (1)
- Phase field model (1)
- Phase field simulation (1)
- Phase stability (1)
- Phase-field model (1)
- Plasticity (1)
- Platform Material Digital (1)
- Platform Material Digital (PMD) (1)
- Platform MaterialDigital (1)
- Platform MaterialDigital (PMD) (1)
- Plattform Material Digital (PMD) (1)
- Polyethylene (1)
- Pore (1)
- Pores (1)
- Porosity (1)
- Positron annihilation spectroscopy (1)
- Power plant (1)
- Precipitate shape (1)
- Precipitates (1)
- Precipitation Analysis (1)
- Precipitation hardening (1)
- Process development (1)
- Quantitative Precipitation Analysis (1)
- Quantitative image analysis (1)
- Radii distribution (1)
- Rafting (1)
- Reference Data (1)
- Reference Dataset (1)
- Reference material BCR-425 (1)
- Referenzmaterial (1)
- Referenzorganismus (1)
- Referenzverfahren (1)
- Reheating (1)
- Relaxation fatigue (1)
- Relaxation tests (1)
- Resonance testing (1)
- Reusability (1)
- Reusable data (1)
- Rissausbreitung (1)
- Risse (1)
- Rissform (1)
- Rissfortschritt (1)
- Rissverlauf (1)
- SEN-Probe (1)
- Safety (1)
- Schadenskunde (1)
- Selective laser melting (1)
- Selective laser melting (SLM) (1)
- Semantic Data Integration (1)
- Semantic Interioerability (1)
- Semantic Web technologies (1)
- Semantic data integration (1)
- Semantic interoperability (1)
- Semantic structuring (1)
- Semantische Daten (1)
- Shape memory alloy (1)
- Shape memory alloys (1)
- Shear testing (1)
- Simulationsgestützte Gießkonzepte (1)
- Single crystal superalloys (1)
- Single-crystal (1)
- Slow crack growth (SCG) (1)
- Solidification (1)
- Spinodal Decomposition (1)
- Spinodal decomposition (1)
- Standardisation (1)
- Strain difference (1)
- Strain energy (1)
- Strength (1)
- Stress-strain behavior (1)
- Stress-strain-behavior (1)
- Structured Data (1)
- Struktur (1)
- Superalloy single crystals (1)
- T1 precipitate (1)
- TIG-welding (1)
- TMF experiments (1)
- Temperature dependence (1)
- Tempered martensite ferritic steels (1)
- Tensile properties (1)
- Tensile strength (1)
- Tensile stress relaxation (1)
- Tensile stress relaxation testing (1)
- Tensile tests (1)
- Texture (1)
- Thermal Cycling (1)
- Thermal expansion (1)
- Thermo-mechanical fatigue (1)
- Thermographie (1)
- Thermomechanical Fatigue (TMF) (1)
- Thermomechanische Ermüdung (1)
- Thermophysikalische Eigenschaften (1)
- Thesaurus (1)
- Thickening (1)
- Tools (1)
- Topography (1)
- Transmission electron microscopy (TEM) (1)
- Tribologie (1)
- Ungleichgewicht (1)
- Unlegierter Baustahl (1)
- Vacancies (1)
- Verbundwerkstoff (1)
- Vernetzung (1)
- Vickers Hardness (1)
- Virtueller Materialdatenraum (1)
- Viskoplastisch (1)
- Visual ontology development (1)
- Vocabulary providers (1)
- Volume fraction (1)
- Werkstoffauswahl (1)
- Werkstoffkennwerte (1)
- Werkstoffmechanische Prüfung (1)
- Werkstoffprüfung (1)
- Workshop (1)
- X-ray computed tomography (CT) (1)
- Young`s modulus (1)
- Young´s modulus (1)
- Zerstörungsfreie Prüfung (1)
- Zugversuchsontologie (1)
- coarsening (1)
- hardness (1)
- microstructural changes (1)
- γ″ phase (1)
- θ′ phase (1)
- θ′-(Al2Cu) precipitate phase (1)
Organisationseinheit der BAM
- 5.2 Metallische Hochtemperaturwerkstoffe (277) (entfernen)
Paper des Monats
- ja (1)
Results of an extended TMF test program on grade P92 steel in the temperature range of 620 °C - 300 °C, comprising in-phase (IP) and out-of-phase (OP) tests, partly performed with symmetric dwells at Tmax/Tmin, are presented. In contrast to previous studies, the low-strain regime is also illuminated, which approaches flexible operation in a power plant with start/stop cycles. At all strain amplitudes, the material performance is characterized by continuous cyclic softening, which is retarded in tests at lower strains but reaches similar magnitudes in the course of testing. In the investigated temperature range, the phase angle does not affect fatigue life in continuous experiments, whereas the IP condition is more detrimental in tests with dwells. Fractographic analyses indicate creep-dominated and fatigue-dominated damage for IP and OP, respectively. Analyses of the (micro)hardness distribution in the tested specimens suggest an enhanced microstructural softening in tests with dwell times for the low- but not for the high-strain regime. To rationalize the obtained fatigue data, the fracture-mechanics-based D_TMF concept, which was developed for TMF life assessment of ductile alloys, was applied. It is found that the D_TMF parameter correlates well with the measured fatigue lives, suggesting that subcritical growth of cracks (with sizes from a few microns to a few millimeters) governs failure in the investigated range of strain amplitudes.
Manufacturing defects, high residual stress (RS), and microstructures affect the structural integrity of laser powder bed fusion (LPBF) Ti-6Al-4V. In this study, the individual effect of these factors on fatigue performance at elevated temperature (300 °C) was evaluated. Material in as-built condition and subjected to post-processing, including two heat treatments and hot isostatic pressing, was investigated. It was found that in the absence of tensile RS, the fatigue life at elevated temperature is primary controlled by the defects; and densification has a much stronger effect than the considered heat treatments on the improvement of the mechanical performance.
Interfacial Spinodals
(2021)
Despite their finite spatial extent, interfaces can have profound impacts on microstructure properties. This is because of their distinct phase-like properties distinguishing them from the adjacent homogeneous bulk structure. When noticed by solute atoms, interfaces can experience their own chemical phase changes. In this talk, we investigate the constrained states of chemically decomposed phases at interfaces. A density-based theory of interfaces is proposed to describe the confined chemical decomposition at general grain boundaries. Here the grain boundary is viewed as a lesser dense, defected structure with reference to the corresponding bulk structure. Using this picture, the thermodynamic origins of interfacial spinodal phenomena are revealed. We also show that transient interfacial spinodals can be activated over a large alloy composition range, enabling kinetic engineering of interfacial chemistry.
Systematic microstructure design requires reliable thermodynamic descriptions and phase diagrams of each and all microstructure elements. While such descriptions are well established for most bulk phases, thermodynamic assessment of crystal defects is greatly challenged by their individualistic aspects. In this talk, we present a density-based thermodynamic concept to describe defects based on available bulk thermodynamic data. Here dealing with grain boundaries (GBs), we apply this concept to compute GB (phase) diagram. Applications to segregation engineering of GBs in bulk and nanocrystalline alloys will be presented. We further develop this model to include the effect of elastic interactions due to atom size mismatch and obtain the corresponding GB (phase) diagram for the ternary Al-Cu-Li system.
The onset of plasticity in a single crystal C60 fullerite was investigated by nanoindentation on the (111) crystallographic plane. The transition from elastic to plastic deformation in a contact was observed as pop-in events on loading curves. The respective resolved shear stresses were computed for the octahedral slip systems ⟨011¯¯¯⟩{111}, supposing that their activation resulted in the onset of plasticity. A finite element analysis was applied, which reproduced the elastic loading until the first pop-in, using a realistic geometry of the Berkovich indenter blunt tip. The obtained estimate of the C60 theoretical shear strength was about 1/11 of the shear modulus on {111} planes.
With an increasing demand in more efficient fuel consumption to reduce CO2 emissions, weight reductions in high-temperature materials at affordable costs gain increasing attention. One potential candidate is the intermetallic material class of iron aluminides, combining the advantages in mass savings, high temperature performance and recyclability of resources. The alloy Fe-26Al-4Mo-0.5Ti-1B was selected to study the microstructural features evolving from two casting processes, five wall thicknesses and three final conditions. Conclusions are drawn upon the correlations of processing variables, grain sizes and hardness.
A phase field model of brittle fracture has been developed to simulate the Hertzian crack induced by penetration of a rigid sphere to an isotropic linear-elastic half-space. The fracture formation is regarded as a diffusive field variable, which is zero for the intact material and unity if there is a crack. Crack growth is assumed to be driven by a strain invariant. The numerical implementation is performed with the finite element method and an implicit time integration scheme. The mechanical equilibrium and the phase field equations are solved in a staggered manner, sequentially updating the displacement field and the phase field variable. Numerical examples demonstrate the capability of the model to reproduce the nucleation and growth of the Hertzian cone crack.
The effectiveness of the mechanism of precipitation strengthening in metallic alloys depends on the shapes of the precipitates. Two different material systems are considered: tetragonal γ′′ precipitates in Ni-based alloys and tetragonal θ′ precipitates in Al-Cu-alloys. The shape formation and evolution of the tetragonally misfitting precipitates was investigated by means of experiments and phase-field simulations. We employed the method of invariant moments for the consistent shape quantification of precipitates obtained from the simulation as well as those obtained from the experiment. Two well-defined shape-quantities are proposed: (i) a generalized measure for the particles aspect ratio and (ii) the normalized λ2, as a measure for shape deviations from an ideal ellipse of the given aspect ratio. Considering the size dependence of the aspect ratio of γ′′ precipitates, we find good agreement between the simulation results and the experiment. Further, the precipitates’ in-plane shape is defined as the central 2D cut through the 3D particle in a plane normal to the tetragonal c-axes of the precipitate. The experimentally observed in-plane shapes of γ′′-precipitates can be quantitatively reproduced by the phase-field model.
Simulation of the θ′ Precipitation Process with Interfacial Anisotropy Effects in Al-Cu Alloys
(2021)
The effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ′-phase (Al2Cu) in Al-1.69 at.% Cu alloy are studied. Multi-phase-field simulations are conducted and discussed in comparison with aging experiments. The precipitate/matrix interface is considered to be anisotropic in terms of its energy and mobility. We find that the additional incorporation of an anisotropic interfacial mobility in conjunction with the elastic anisotropy result in substantially larger aspect ratios of the precipitates closer to the experimental observations. The anisotropy of the interfacial energy shows comparably small effect on the precipitate’s aspect ratio but changes the interface’s shape at the rim. The effect of the chemo-mechanical coupling, i.e., the composition dependence of the elastic constants, is studied as well. We show that the inverse ripening phenomenon, recently evidenced for δ’ precipitates in Al-Li alloys (Park et al. Sci. Rep. 2019, 9, 3981), does not establish for the θ′ precipitates. This is because of the anisotropic stress fields built around the θ′ precipitates, stemming from the precipitate’s shape and the interaction among different variants of the θ′ precipitate, that disturb the chemo-mechanical effects. These results show that the chemo-mechanical effects on the precipitation ripening strongly depend on the degree of sphericity and elastic isotropy of the precipitate and matrix phases.
Phase diagrams are the roadmaps for designing bulk phases. Similar to bulk, grain boundaries can possess various phases, but their phase diagrams remain largely unknown. Using a recently introduced density-based model, here we devise a strategy for computing multi-component grain boundary phase diagrams based on available bulk (CALPHAD) thermodynamic data. Fe-Mn-Cr, Fe-Mn-Ni, Fe-Mn-Co, Fe-Cr-Ni and Fe-Cr-Co alloy systems, as important ternary bases for several trending steels and high-entropy alloys, are studied. We found that despite its solute segregation enrichment, a grain boundary can have lower solubility limit than its corresponding bulk, promoting an interfacial chemical decomposition upon solute segregation. This is revealed here for the Fe-Mn-base alloy systems. The origins of this counter-intuitive feature are traced back to two effects, i.e., the magnetic ordering effect and the low cohesive energy of Mn solute element. Different aspects of interfacial phase stability and GB co-segregation in ternary alloys are investigated as well. We show that the concentration gradient energy contributions reduce segregation level but increase grain boundary solubility limit, stabilizing the GB against a chemical decomposition. Density-based grain boundary phase diagrams offer guidelines for systematic investigation of interfacial phase changes with applications to microstructure defects engineering.
The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufacturing (hot isostatic pressing) as well as during technical accidents which may happen in service (overheating). High reliability of the results was achieved using specimens of different crystallographic orientations, exciting various vibration modes as well as precise measurement of the material density and thermal Expansion required for modeling the resonance frequencies by finite element method. Combining the results measured in this work and literature data the elastic constants of the gamma and gamma' phases were predicted.
This prediction was supported by measurement of the temperature dependence of the gamma'fraction.
All data obtained in this work are given in numerical or analytical forms and can be easily used for different scientific and engineering calculations.
The aluminum alloy 2618A is applied for engine components such as radial compressor wheels which operate for long time at elevated temperatures. This results in coarsening of the hardening precipitates and degradation in mechanical properties during the long-term operation, which is not taken into account in the current lifetime prediction models due to the lack of quantitative microstructural and mechanical data. To address this issue, a quantitative investigation on the evolution of precipitates during long-term aging at 190 °C for up to 25,000 h was conducted. Detailed transmission electron microscopy (TEM) was combined with Brinell hardness measurements and thorough differential scanning calorimetry (DSC) experiments. The results showthat GPB zones and S-phase Al2CuMg grow up to < 1,000 h during which the GPB zones dissolve and S-phase precipitates form. For longer aging times, only S-phase precipitates coarsen, which can be well described using the Lifshitz–Slyozov Wagner theory of ripening. A thorough understanding of the underlying microstructural processes is a prerequisite to enable the integration of aging behavior into the established lifetime models for components manufactured from alloy 2618A.
Segregation to grain boundaries affects their cohesion, corrosion, and embrittlement and plays a critical role in heterogeneous nucleation. In order to quantitatively study segregation and low-dimensional phase separation at grain boundaries, here, we apply a density-based phase-field model. The current model describes the grain-boundary thermodynamic properties based on available bulk thermodynamic data, while the grain-boundary-density profile is obtained using atomistic simulations. To benchmark the performance of the model, Mn grain-boundary segregation in the Fe–Mn system is studied. 3D simulation results are compared against atom probe tomography measurements conducted for three alloy compositions. We show that a continuous increase in the alloy composition results in a discontinuous jump in the segregation isotherm. The jump corresponds to a spinodal Phase separation at grain boundary. For alloy compositions above the jump, we reveal an interfacial transient spinodal phase separation.
The transient spinodal phenomenon opens opportunities for knowledge-based microstructure design through the chemical manipulation of grain boundaries. The proposed density-based model provides a powerful tool to study thermodynamics and kinetics of segregation and phase changes at grain boundaries.
Additively manufactured metallic materials have already started to find application in safety-relevant components. However, this has only happened for certain materials and specific applications and loading conditions, since there is still an extensive lack of knowledge as well as of historical data regarding their mechanical behaviour. This contribution aims to address this lack of understanding and historical data concerning the creep behaviour of the austenitic stainless steel 316L manufactured by Laser-Powder-Bed-Fusion (L-PBF) and the low-cycle-fatigue behaviour of the titanium alloy Ti-6Al-4V manufactured by Laser-Metal-Deposition (LMD). Furthermore, it aims to assess their mechanical behaviour against their conventional counterparts. With that in mind, specimens from conventional and additive materials are tested and their mechanical behaviour analysed based on characteristic curves. To understand the damage behaviours the materials are characterized by destructive and non-destructive techniques before and after failure.
Eine kritische Aufgabe im Rahmen der Etablierung von Prozess-Struktur-Eigenschafts-Performance-Beziehungen bei der additiven Fertigung (AM) von Metallen ist die Ermittlung von zuverlässigen und gut dokumentierten Kennwerten zum Materialverhalten sowie das Schaffen von Wissen über die Struktur-Eigenschafts-Korrelation. Schließlich ist dies die Grundlage für die Entwicklung gezielterer Prozessoptimierungen und zuverlässigerer Lebensdauer-Vorhersagen. In diesem Zusammenhang zielt dieser Beitrag darauf ab, Daten und Erkenntnisse über das Kriechverhalten des austenitischen Edelstahls 316L zu liefern, der mittels Laser-Powder-Bed-Fusion (L-PBF) hergestellt wird. Um dieses Ziel zu erreichen, wurden Proben aus konventionellem warmgewalztem sowie AM-Material gemäß den bestehenden Normen für konventionelles Material geprüft und vor und nach dem Versagen mikrostrukturell charakterisiert. Die Probekörper wurden aus einzelnen Blöcken des AM-Materials gefertigt. Die Blöcke wurden mit einer Standard-Scan- und Aufbaustrategie hergestellt und anschließend wärmebehandelt. Das Kriechverhalten wird anhand der Kriechlebensdauer und ausgewählter Kriechkurven und Kennwerte beschrieben und vergleichend bewertet. Der Einfluss von Defekten und Mikrostruktur auf das Materialverhalten wird anhand von zerstörenden und zerstörungsfreien Auswertungen an ausgewählten Proben analysiert. Der AM-Werkstoff zeigt kürzere Kriechlebensdauern, erreicht das sekundäre Kriechstadium deutlich schneller und bei geringerer Dehnung und weist eine geringere Kriechduktilität im Vergleich zu seinem konventionellen Gegenstück auf. Das Kriechschädigungsverhalten des AM-Werkstoffs ist eher mikrostruktur- als defektgesteuert und ist durch die Bildung intergranularer Kriechrisse gekennzeichnet. Als kritische Merkmale werden die Versetzungsdichte sowie die Versprödung der Korngrenzen identifiziert. Die Mikro-Computertomographie (µCT) erweist sich als Alternative zur Metallographie, um die Kriechschädigung zu analysieren.
Creep and fracture behavior of conventionally and additively manufactured stainless steel 316L
(2020)
A critical task within the frame of establishing process-structure-property-performance relationships in additive manufacturing (AM) of metals is producing reliable and well-documented material behavior’s data and knowledge regarding the structure-property correlation, including the role of defects. After all, it represents the basis for developing more targeted process optimizations and more reliable predictions of performance in the future. Within this context, this contribution aims to close the actual gap of limited historical data and knowledge concerning the creep behavior of the widely used austenitic stainless steel 316L, manufactured by Laser-Powder-Bed-Fusion (L-PBF). To address this objective, specimens from conventional hot-rolled and AM material were tested under application-relevant conditions according to existing standards for conventional material, and microstructurally characterized before and after failure. The test specimens were machined from single blocks from the AM material. The blocks were manufactured using a standard scan and build-up strategy and were subsequently heat-treated. The creep behavior is described and comparatively assessed based on the creep lifetime and selected creep curves and characteristic values. The effect of defects and microstructure on the material’s behavior is analyzed based on destructive and non-destructive evaluations on selected specimens. The AM material shows shorter creep lives, reaches the secondary creep stage much faster and at a lower strain, and features lower creep ductility compared to its conventional counterpart. The creep damage behavior of the AM material is more microstructure than defect controlled and is characterized by the formation and accumulation of single intergranular damage along the whole volume. Critical features identified are the grain morphology and the grain-boundary as well as the dislocation’s density. Micro-computed tomography (µCT) proves to be an alternative to metallography to analyze the creep damage.
Mit Hilfe des HIP-Verfahrens („Hot Isostatic Pressing“) werden Poren in der einkristallinen Nickel-Basis Superlegierung CMSX-4 kontinuierlich geschrumpft und dadurch die nach der Erstarrung und der Wärmebehandlung vorhandene Porosität stark reduziert. In diesem Beitrag werden experimentelle und numerische Untersuchungen zu den Mechanismen der Porenschrumpfung zusammengefasst. Es zeigt sich, dass das Verformungsverhalten während Kriechversuchen bei der HIP-Temperatur durch Versetzungsgleitung auf oktaedrischen Ebenen dominiert wird.
Dagegen zeigen Messungen der Porositätsabnahme und Simulationen des Porenschließens, dass die Kinetik der Porenschrumpfung durch das Phänomen der Leerstellendiffusion zwischen Poren und Kleinwinkelkorngrenzen („Low Angle Boundary“, LAB) bestimmt wird. Im Gegensatz führt die klassische Kristallviskoplastizität zu einer systematischen Überschätzung dieser Kinetik. Der scheinbare Widerspruch lässt sich auflösen, wenn man bedenkt, dass auf der Skala der Poren Versetzungsquellen nicht gleichmäßig verteilt sind, wie in der konventionellen Kristallplastizität implizit angenommen wird. Stattdessen wird in einem weiterführenden Modell davon ausgegangen, das Kleinwinkelkorngrenzen (LABs) als Versetzungsquellen fungieren, während die Scherspannungen sehr stark in der Nähe der Poren lokalisiert sind, was die Emission von Versetzungen deutlich reduziert.
Mit Hilfe des HIP-Verfahrens („Hot Isostatic Pressing“) werden Poren in der einkristallinen Nickel-Basis Superlegierung CMSX-4 kontinuierlich geschrumpft und dadurch die nach der Erstarrung und der Wärmebehandlung vorhandene Porosität stark reduziert. In diesem Beitrag werden experimentelle und numerische Untersuchungen zu den Mechanismen der Porenschrumpfung zusammengefasst. Es zeigt sich, dass das Verformungsverhalten während Kriechversuchen bei der HIP-Temperatur durch Versetzungsgleitung auf oktaedrischen Ebenen dominiert wird.
Dagegen zeigen Messungen der Porositätsabnahme und Simulationen des Porenschließens, dass die Kinetik der Porenschrumpfung durch das Phänomen der Leerstellendiffusion zwischen Poren und Kleinwinkelkorngrenzen („Low Angle Boundary“, LAB) bestimmt wird. Im Gegensatz führt die klassische Kristallviskoplastizität zu einer systematischen Überschätzung dieser Kinetik. Der scheinbare Widerspruch lässt sich auflösen, wenn man bedenkt, dass auf der Skala der Poren Versetzungsquellen nicht gleichmäßig verteilt sind, wie in der konventionellen Kristallplastizität implizit angenommen wird. Stattdessen wird in einem weiterführenden Modell davon ausgegangen, das Kleinwinkelkorngrenzen (LABs) als Versetzungsquellen fungieren, während die Scherspannungen sehr stark in der Nähe der Poren lokalisiert sind, was die Emission von Versetzungen deutlich reduziert.