Phase transformations and crystallographic defects are two essential tools todrive innovations in materials. Bulk materials design via tuning chemicalcompositions is systematized using phase diagrams. It is shown here that thesame thermodynamic concept can be applied to manipulate the chemistry atdefects. Grain boundaries in Mg–Ga system are chosen as a model system,because Ga segregates to the boundaries, while simultaneously improving thestrength and ductility of Mg alloys. To reveal the role of grain boundaries,correlated atomic-scale characterization and simulation to scope and buildphase diagrams for defects are presented. The discovery is enabled bytriggering phase transformations of individual grain boundaries through localalloying, and sequentially imaging the structural and chemical changes usingatomic-resolution scanning transmission electron microscopy. Ab initiosimulations determined the thermodynamic stability of grain boundaryphases, and found out that increasing Ga content enhances grain boundarycohesion, relating to improved ductility. The methodology to trigger, trace,and simulate defect transformation at atomic resolution enables a systematicdevelopment of defect phase diagrams, providing a valuable tool to utilizechemical complexity and phase transformations at defects.
A Lightweight Procedural Layer for Hybrid Experimental–Computational Workflows in Materials Science
(2026)
We present a prototype implementation of a framework for hybrid workflows that integrates automated computation and analysis with manual experimental measurements. Leveraging the pyiron workflow engine, we introduce a lightweight, parameterized procedure description layer that can adjust instrument settings and orchestrate human interventions. Rather than replacing the existing execution engine, we add a minimal abstraction layer that translates procedure descriptions into executable steps for manual operations, enabling seamless handoffs between automated tasks and manual experimental tasks. We demonstrate the approach on a use case that combines manual tensile testing with subsequent analytical evaluation and result aggregation, illustrating how parameters and metadata propagate through the workflow and how instrument state changes and measurement results are captured. We also report a usability study that quantifies the ease with which lab scientists can create and modify workflows. Finally, we summarize lessons learned from this prototype, including improved provenance capture and streamlined experimental orchestration, as well as current limitations. We conclude that the proposed lightweight hybrid workflow description offers a promising path to bridging automation, computation and manual experimentation, and we outline directions for future work.
One of the main challenges for the synthesis and application of the promising hard-magnetic compound CeFe11Ti is the formation of Laves phases that are detrimental for their thermodynamic stability and magnetic properties. In this paper, we present an ab initio based approach to modify the stability of these phases in the Ce-Fe-Ti system by additions of 3d and 4d elements. We combine highly accurate free-energy calculations with an efficient screening technique to determine the critical annealing temperature for the formation of Ce(Fe,X)11Ti. The central findings are the dominant role of the formation enthalpy at T = 0 K on chemical trends and the major relevance of partial chemical decompositions. Based on these insights, promising transition metals to promote the stability of the hard-magnetic phase, such as Zn and Tc, were predicted. The comparison with suction casting and reactive crucible melting experiments for Ce-Fe-Ti-X (X = Cu, Ga, Co, and Cr) highlights the relevance of additional phases and quaternary elements.
Thermodynamic bulk phase diagrams have become the roadmap used by researchers to identify alloy compositions and process conditions that result in novel materials with tailored properties. Recent experimental studies show that changes in the alloy composition can drive not only transitions in the bulk phases present in a material, but also in the concentration and type of defects they contain. Defect phase diagrams in combination with density functional theory provide a natural route to study these chemically driven defects.
Our results reveal, however, that direct application of equilibrium bulk thermodynamics can fail to reproduce experimentally observed defect formation. Therefore, we extend the concept to metastable defect phase diagrams to account for kinetic limitations that prevent the system from reaching equilibrium. We apply this concept to successfully explain the formation of large concentrations of planar defects in supersaturated Fe-Nb solid solutions. We then utilize it to design suitable conditions for synthesis, which we subsequently realized experimentally, successfully validating the formation of the predicted defects in Mg-Al-Ca alloys. The concept offers new avenues for the design of materials performance by tailoring defect structures.
Segregation of alloying elements and impurities at grain boundaries (GBs) critically influences material behaviour by affecting cohesion. In this study, we present an ab initio high-throughput evaluation of segregation energies and cohesive effects for all elements up to Z=92 in the periodic table (Z = 1–92, H–U) across the substitutional sites in six model ferritic iron GBs using density functional theory (DFT). From these data, we construct comprehensive elemental maps for solute segregation tendencies and cohesion at GBs, providing guidance for segregation engineering. We systematically assess the cohesive effects of different elements in all segregating positions along multiple fracture paths with a quantum-chemistry bond-order method as well as a modified Rice–Thomson–Wang theory of interfacial cohesion. The effects of segregants on the cohesion of GBs are shown to vary drastically as a function of site character, and hence their induced cohesive effects must
be considered as a thermodynamic average over the spectral energy distribution. Thus, models that overlook these aspects may fail to accurately predict the impacts of varying alloying concentrations, thermal processing conditions, or GB types. The insights presented here, along with our accompanying dataset, are expected to advance our understanding of GB segregation in steels and other materials.
Life Cycle Assessment (LCA) and Social Life Cycle Assessment (SLCA) are applied in evaluating possible social and environmental impacts of the state-of-art welding technologies, such as Manual Metal Arc Welding (MMAW), Manual Gas Metal Arc Welding (GMAW), Automatic GMAW and Automatic Laser-Arc Hybrid Welding (LAHW). The LCA results indicate that for 1 meter weld seam, MMAW consumes the largest amount of resources (like filler material and coating on electrodes) and energy, which contributes to comparatively higher environmental impacts in global warming potential, acidification, photochemical ozone creation potential and eutrophication than other chosen processes. With regard to social aspects, the health issues and fair salary are under survey to compare the relative potential risk on human health caused by fumes in different welding technologies, and to indicate the sufficiency of current salary of welders in Germany. The results reflect that the wage status of welders is still fair and sufficient. The manual processes bring much higher potential risk of welders health than the automatic processes, especially MMAW.
Evaluating innovative process technologies has become highly important within the last decades. As standard tools different Life Cycle Assessment methods have been established, which are continuously improved. While those are designed for evaluating single processes they run into difficulties when it comes to assessing environmental impacts of process innovations at macroeconomic level. In this paper we develop a multi-step evaluation framework building on multi regional inputeoutput data that allows estimating macroeconomic impacts of new process technologies, considering the network characteristics of the global economy.
Our procedure is as follows: i) we measure differences in material usage of process alternatives, ii) we identify where the standard processes are located within economic networks and virtually replace those by innovative process technologies, iii) we account for changes within economic systems and evaluate impacts on emissions.
Within this paper we exemplarily apply the methodology to two recently developed innovative technologies: longitudinal large diameter steel pipe welding and turning of high-temperature resistant materials. While we find the macroeconomic impacts of very specific process innovations to be small, its conclusions can significantly differ from traditional process based approaches. Furthermore, information gained from the methodology provides relevant additional insights for decision makers extending the picture gained from traditional process life cycle assessment.
