Metals

The development of efficient and sustainable hydrogen storage materials is a key challenge for realizing hydrogen as a clean and flexible energy carrier. Among various options, metal hydrides offer high volumetric storage density and operational safety, yet their application is limited by thermodynamic, kinetic, and compositional constraints. In this work, we investigate the potential of machine learning (ML) to predict key thermodynamic properties—equilibrium plateau pressure, enthalpy, and entropy of hydride formation—based solely on alloy composition using Magpie-generated descriptors. We significantly expand an existing experimental dataset from ~400 to 806 entries and assess the impact of dataset size and data augmentation, using the PADRE algorithm, on model performance. Models including Support Vector Machines and Gradient Boosted Random Forests were trained and optimized via grid search and cross-validation. Results show a marked improvement in predictive accuracy with increased dataset size, while data augmentation benefits are limited to smaller datasets and do not improve accuracy in underrepresented pressure regimes. Furthermore, clustering and cross-validation analyses highlight the limited generalizability of models across different material classes, though high accuracy is achieved when training and testing within a single hydride family (e.g., AB₂). The study demonstrates the viability and limitations of ML for accelerating hydride discovery, emphasizing the importance of dataset diversity and representation for robust property prediction.

Ni and Ni/basalt (Ni/Bst) coatings prepared by the electrodeposition on Mo substrate were analyzed with the aim of their potential application in forensics. The coatings of Ni and Ni/Bst are produced galvanostatically from the sulfamate electrolyte at different current densities and characterized by scanning electron microscope (morphology), X-ray diffraction (structure) and Vickers microindentation (microhardness). The wettability of Ni and Ni/Bst coatings was also investigated. While morphology and microhardness of the coatings strongly depended on the current density of electrodeposition and the presence of basalt particles in the electrolyte, the effect of basalt addition on structure of the coatings was not observed. The microhardness of Ni coatings was in the (1.6951–5.7246) GPa range, while the addition of basalt particles increased the range to (5.8206–10.7981) GPa. Both Ni and Ni/Bst coatings were hydrophilic, whereas comparison of the coatings obtained at the same current density showed that incorporation of the basalt particles in the coating decreases the degree of hydrophilicity, as observed by the increase in the water contact angle (WCA). The largest WCA, i.e., the smallest hydrophilicity, showed Ni/Bst coating produced at 30 mA cm⁻² (WCA ≈ 75.5°), and was about 46.7% larger than that of Mo substrate (WCA ≈ 51.5°). This coating also showed the best development of latent fingerprints with clearly visible ridge details, indicating that there is strong correlation between fingerprint development and the wettability of the coatings.

TA2 titanium was brazed with a Ti–37.5Zr–15Cu–10Ni filler metal at 860–890 °C for 20 min to investigate the influence of temperature on joint properties. Raising the brazing temperature reduced residual filler in the seam center and transformed the microstructure from heterogeneous phases to a uniform α-(Ti,Zr) solid-solution matrix, accompanied by significant widening of the diffusion layer. At brazing temperatures of 890 °C, the hardness decreased to below 300 HV_0.5 and became more uniform as brittle phases were suppressed. The shear strength reached a maximum of 302 MPa, and the fracture morphology exhibited characteristics of ductile fracture. Micro-electrochemical testing indicated that the joint brazed exhibited an almost uniform current distribution and significantly reduced localized corrosion. Although a small fraction of the Widmanstätten structure was observed at this temperature, it did not impair the overall mechanical performance. These findings demonstrate that a moderate increase in brazing temperature promotes elemental diffusion, alleviates brittle phase enrichment, and markedly enhances the mechanical properties and corrosion resistance of TA2 joints.