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Materials Science and Engineering (MSE) increasingly relies on data‐intensive, automated, and distributed workflows that span synthesis, manufacturing, characterization, design, and simulation. These settings require machine‐actionable representations of materials and processes that remain interoperable across laboratories, software stacks, and organizations. Therefore, Platform MaterialDigital Core Ontology (PMDco) 3.0 is introduced as a mid‐level ontology that provides a semantic framework for the processing–structure–properties paradigm in MSE. PMDco 3.0 adopts an architecture aligned with the Basic Formal Ontology that enables a logically consistent classification of fundamental MSE concepts and the explicit representation of intrinsic material properties, contextual roles and functions, and related information artifacts. The work outlines the technical curation approach that supports sustainable ontology evolution through reproducible builds, automated release generation, and systematic validation workflows. Representative semantic patterns are presented as reusable building blocks for consistent modeling and data mapping, including material object duality, intensive versus extensive qualities, role and function assignment, immaterial entities for spatial context, process modeling across production, assay, and computation, and the separation of requirements from observations via set points and measurements. PMDco 3.0 is intended to serve as a community‐driven anchor for interoperable domain and application ontologies and scalable semantic interoperability in MSE.
Current and future directions in probing structural dynamics and transport of metallic glasses
(2026)
In this article, we discuss the challenges in assessing dynamics and structural changes of metallic glasses as amorphous out-of-equilibrium materials by means of coherent x-ray scattering. We focus on the fundamental understanding of the x-ray photon correlation spectroscopy (XPCS) technique and on how such an experimental probe may facilitate a deeper quantitative understanding of the underlying structural fluctuations occurring within the amorphous solid. Furthermore, we present how atomistic simulations and simulated x-ray photon correlation spectroscopy experiments can guide the interpretation of experimentally measured data. We conclude with a broader perspective on how contemporary advances in modeling, detector technology, and high flux x‑ray sources are transforming the study of glassy dynamics, enabling access to wider time and length scales and thus offering new avenues to probe the broad relaxation spectrum and complex nonequilibrium relaxation processes characteristic of amorphous solids.
Liquid-metal embrittlement (LME) in Zn-coated steels is traditionally understood as a consequence of liquid Zn penetration along grain boundaries (GBs) during thermo-mechanical processing. However, recent thermodynamic predictions brought to light a massive Zn segregation transition at Fe GBs that suggest a strong driving force for intermetallic phase formation at substantially lower temperatures than the melting point of Zn. Leveraging bulk mechanical testing, high-energy synchrotron diffraction, and transmission electron microscopy, we demonstrate here that embrittling Fe-rich intermetallic grain-boundary phases emerge in an advanced high-strength steel prior to any melting of Zn. Their formation and increasing presence with temperature correlates with severe mechanical degradation. These findings provide consistent evidence that the solid-state formation of Fe-rich Fe-Zn intermetallic phases constitutes an early contributing step to LME in galvanized high-strength steels.
Phase separation is a well‐known approach to increase the damage tolerance of oxide glasses. Here, we report the separation of a silicon‐ and boron‐rich phase in a Si‐poor sodium‐borosilicate glass. This phase separation follows initially a strongly suppressed growth‐law, shows a droplet to needle morphology phase evolution, and exhibits a phase inversion. We discuss the phase separation and inversion in terms of structural mobility constraints and internal stresses. Once a needle‐dominated phase morphology is established, a marked increase of of the indentation fracture toughness and an enhanced crack resistance by more than a factor of 5 is observed.
With recent advances in generative machine learning, different models have been adapted to predict novel materials, and new architectures are emerging frequently. While several metrics allow for the rating of individual characteristics (e.g., quality or novelty) of generated crystal structures on an instance level, approaches that evaluate the general performance of generative models for materials prediction are missing. To close this gap, we developed the Transport Novelty Distance (TNovD).
This metric evaluates generative models by jointly judging the novelty and quality of all newly generated crystal structures. Thereto, the Wasserstein distance is calculated on an abstract feature space distribution derived from the chemical and physical characteristics of the materials. These features are created by embedding the crystals description with an invariant Graph Neural Network (GNN) that was trained with the InfoNCE loss on the identical set of materials as the generative model. Using contrastive learning allows to not only account for materials themselves, but also for their augmented counterparts and differently sized supercells. Based on the resulting feature space, couplings between generated and train set are calculated and split into a quality and a memorization regime by a threshold. This allows to evaluate quality and novelty simultaneously.
The TNovD was tested on various toy experiments for memorization and different cases of crystal structure degeneration. Additionally, we validated it on the MP20 validation set and the WBM substitution dataset. The experiments results demonstrate the TNovD capabilities of detecting both memorization and low-quality materials. Afterwards, we benchmark the performance of several popular material generative models with the MP20 validation data. While introduced for materials, our TNovD framework is domain-agnostic and can be adapted for other areas in the space of chemical compounds, such as images and molecules.
Understanding the structural origins of thermal expansion in metallic glasses (MGs) is essential for engineering next-generation materials with high thermal stability and performance. Accordingly, we used molecular dynamics simulations to investigate how local atomic motifs control the thermal expansion of MGs. Motif-resolved analysis using Voronoi tessellation reveals that mixed polyhedra are the main contributors to macroscopic thermal expansion, whereas icosahedral units act as stabilizers that resist volume changes. This interpretation is supported by motif-resolved potential-energy analysis, which shows lower, more temperature-stable energies for icosahedral polyhedra, in contrast to the strongly anharmonic response of mixed polyhedra. To connect motif-level thermal expansion to atomic-scale behavior, we analyzed bonds using the radial probability function (𝐺(𝑟)). A skewed-normal fit to the first peak shows a monotonic increase in mean interatomic distance with temperature, resolving the apparent contraction reported in earlier studies relying solely on the position of the first peak of 𝐺(𝑟). Overall, this work establishes a coherent structural picture for thermal expansion in MGs. The consistent behavior across the investigated alloys demonstrates that icosahedral units are systematically associated with lower local expansion, while mixed polyhedra dominate the macroscopic thermal response. This motif-dependent behavior is robust across different compositions, interatomic potentials, and cooling rates, providing a basis for designing MGs with improved thermal stability.
Discovering sustainable glass compositions demands navigating vast chemical spaces—a challenge that conventional experimentation cannot meet efficiently. Here we introduce the Simulation-Calibrated Active Learning Estimator (SCALE), a closed-loop framework uniting high-throughput molecular dynamics (MD), machine learning (ML), and robotic synthesis to bridge the gap between simulation and experiment. Over 42,000 melt–quench MD simulations with compact cells (≈ 200–500 atoms) train ML models that predict density and elastic moduli with cross-validated R2 values up to 0.98. Comparison with 55 robotically synthesized sodium alumino-borosilicate glasses reveals systematic density overestimation of up to 5%. Rather than naively augmenting training data, SCALE iteratively learns a composition-dependent calibration from minimal targeted measurements. The protocol substantially reduces density errors over three experimental iterations of six measurements each and demonstrates the potential for glass optimization with a small number of strategically chosen experiments.
Generative machine learning is increasingly used for inorganic crystal structure generation. Most models and the corresponding evaluation approaches rely on simple forms of crystal structure representation. In this paper, we showcase the power of atom-averaged features from pretrained Machine-Learning Interatomic Potentials (MLIPs), such as MACE, for such tasks. We first introduce a distance measure that assesses the output of material generative models by capturing both quality and novelty in a single distribution-based evaluation framework. In particular, we introduce the Coarse-Fine Transport Distance (CFTD) using two different featurizers, where the quality component is based on coarse MACE features. We showcase CFTD’s versatility in capturing crystal-structure quality while also detecting memorization, and compare it with the recently introduced continuous SUN metrics. We further show that coarse MACE features can be used as guidance for a material generative model.
Chronic wounds present alkaline pH commonly associated to frequent infections, making pH monitoring useful to follow the healing process and to guide antibacterial treatments. This work aims to develop a multifunctional natural polymer-based wound dressing embedded with a bioactive glass and a natural dye, enabling healing, antibacterial activity, and colorimetric pH sensing. Preliminary results confirm mechanical flexibility, bioactivity, and measurable pH responsive behavior of the dressings.
Ensuring chemical homogeneity is critical not only for the fabrication of commercial glasses and glass-ceramics with reliable performance, but also for fundamental studies in glass science, where this property is often a core assumption. Therefore, the development of simple procedures to assess the chemical homogeneity of glasses is of significant interest to the glass community. In this context, we implemented and evaluated, for the first time, a statistical method to determine the microstructural uniformity of partially crystallized glasses using the aggregation index (R), a parameter derived from the Poisson distribution. The R-index quantifies deviations of an observed spatial distribution of objects from an ideal homogeneous (random) arrangement, enabling the identification of clustering or periodic patterns indicative of inhomogeneity.
Since crystal nucleation in glasses is strongly influenced by the chemical composition of the parent glasses, particularly the local disposition of constituent elements, the spatial distribution of crystals in derived glass-ceramics can be used as an indirect measure of chemical homogeneity. To test this approach, we conducted a nearest-neighbor statistical analysis of the spatial crystal arrangement in partially crystallized Li2Si2O5 and Ba5Si8O21 glasses, using optical micrographs acquired at different magnifications. The resulting R-indices indicate a high degree of homogeneity in the microstructure of the analyzed glass-ceramics, reflecting a uniform distribution of chemical elements in the correspondent parent glasses. These results demonstrate that the 𝑅-index is a valuable and easily implemented tool for assessing the chemical homogeneity of internally nucleating glasses.