Laser additive manufacturing involves intrinsic rapid solidification rate and elemental segregation, which induce thermal residual stress and metastable microstructures, potentially leading to mechanical performance degradation. To address this, we tailored stacking fault energy (SFE) and hierarchical precipitation to enable near-full recrystallization in a Ni-based multi-principal element alloy. Guided by phase diagram calculation and density functional theory, a Ni-Cr-Fe-Co matrix with Al/Ti/V additions was designed and fabricated to stabilize a medium-level intrinsic SFE while forming hierarchical precipitates (primary BCC/B2 and secondary nanoscale acicular phases) via direct energy deposition in-situ alloying. Uniformly distributed precipitates nucleate preferentially within the grains, with limited formation at the boundaries. This microstructural change further promotes dynamic recrystallization under inherent severe plastic deformation. Consequently, the as-deposited alloy developed ∼92% recrystallized grains and exhibited a yield strength of 790 MPa, ultimate tensile strength of 1164 MPa, and uniform elongation of 24.6%, while multiscale characterizations confirmed plastic deformation interaction of precipitation within the recrystallized grains. This study demonstrates that engineering SFE and hierarchical precipitations promote dynamic recrystallization and synergetic mechanical properties, offering a generalizable strategy for additively manufactured Ni-based alloys.

The vacancy formation is inevitable in the hydrogen storage process of medium-entropy alloys (MEAs) and high-entropy alloys (HEAs). However, hydrogen-vacancy interactions in MEA and HEA hydrides remain poorly understood. In this study, we employ first-principles calculations to investigate the energetic stability of hydrogen occupying a vacancy in Ti_0.25V_0.25Zr_0.25Nb_0.25 MEA hydride. In the defective hydride, hydrogen preferentially occupies tetrahedral interstitial (T) sites surrounding the vacancy, followed by regular T sites. Once all T sites are occupied, introducing hydrogen into the vacancy results in two distinct behaviors upon structural optimization. In one case, the hydrogen atom spontaneously migrates out of the vacancy, indicating that positions surrounding the vacancy are energetically more favorable for hydrogen occupation than the vacancy itself. In the other case, the hydrogen atom remains in the vacancy but exhibits a positive formation energy, suggesting that hydrogen is energetically unfavorable and unstable at the vacancy site. Using chemical bonding analysis, we demonstrate that the instability of hydrogen in vacancy is weakly related to the metal-hydrogen interactions. Instead, the hydrogen occupying the vacancy form strong antibonding states with nearest-neighbor hydrogen atoms, contributing to the instability. Our study provides an atomistic-level understanding of hydrogen behavior at a vacancy, enhancing the broader understanding of hydrogen storage in MEAs and HEAs.

The design and optimization of mechanically hard soft magnetic materials, which combine high hardness with magnetically soft properties, represent a critical frontier in materials science for advanced technological applications. To address this challenge, a data-driven framework is presented for exploring the vast compositional space of high-entropy alloys (HEAs) and identifying candidates optimized for multifunctionality. The study employs a comprehensive dataset of 1 842 628 density functional theory calculations, comprising 45 886 quaternary and 414 771 quinary equimolar HEAs derived from 42 elements. Using ensemble learning, predictive models are integrated to capture the relationships between composition, crystal structure, mechanical, and magnetic properties. This framework offers a robust pathway for accelerating the discovery of next-generation alloys with high hardness and magnetic softness, highlighting the transformative impact of data-driven strategies in material design.

We investigate how the Al content in Alx(Mn0.76Co0.24)1-x (x = 0.45, 0.50, 0.55) alloys and the Mn/Co ratio in Al0.50MnyCo0.50-y (y = 0.36, 0.38, 0.40) alloys affect the magnetic properties. Structural and magnetic investigations by experiments, Thermo-Calc, and ab initio calculations show a dual-phase microstructure containing different fractions of a paramagnetic body-centered cubic (BCC) solid solution and a ferromagnetic B2 phase. The BCC/B2 phase fraction is sensitive to the Al content which strongly affects the saturation magnetization, magnetic transition temperature, and magnetocaloric properties. The magnetocaloric properties of the Al0.50Mn0.38Co0.12 alloy show peak values around 430 K with a magnetic entropy change of 0.71 Jkg−1K−1, an adiabatic temperature change of 0.40 K, and a refrigeration capacity of 25.56 Jkg−1 under a magnetic field of 650 kAm−1 (0.82 T). These results open new possibilities for identifying promising medium-entropy alloys for magnetocaloric applications.

Vanadium-based materials have great potential for advancing novel hydrogen storage technology. To address the limited gravimetric hydrogen storage capacity of V, incorporating light alloying elements has been proposed. In this study, the hydrogen storage capacities of V1−xAlx (x = 0, 0.1, 0.2, 0.3, and 0.4) solid solutions are investigated by employing first-principles calculations. Our results indicate that both the stability and hydrogen storage capacity of V1−xAlx hydrides decrease with an increase in Al content due to a reduction of chemical contribution, consistent with experimental results. The chemical bond analysis, Bader charge, and projected density of states investigation reveal that the Al-H antibonding states appear at the Fermi level and net H-H antibonding states surrounding Al form due to the transfer of excessive electrons from Al to H. To further explore the relationship between chemical bonding and desorption enthalpy, over 20 face-centered cubic (FCC) metal dihydrides are selected. It is found that the desorption enthalpies correlate weakly with the metal-hydrogen (M-H) bond strength and positively with M-H antibonding states below the Fermi level. Our study reveals the mechanism of interactions between chemical bonds and hydrogen storage properties in metal hydrides, providing valuable insights for the future design of hydrogen storage materials.

This study investigates the magnetocaloric potential of the Al50Cr21-xMn17+xCo12 (x=0, 4, 8 at%) high-entropy alloy (HEA) series using integrated experimental and theoretical approaches. Structural analysis by X-ray diffraction and scanning electron microscopy indicate a dual phase containing B2 and body-centered cubic (BCC) structures. Magnetic characterization shows an approximately linear decrease in saturation magnetization and Curie temperature with increasing Cr content. Curie temperatures calculated by Monte Carlo simulations suggest that the measured magnetic properties originate from the B2 phase rather than the BCC phase. The enhanced magnetocaloric effect with decreasing Cr content highlights the attractiveness of HEAs in magnetocaloric applications.

Refractory high-entropy alloys (HEAs) show promise for novel hydrogen storage technology, but addressing their limited gravimetric hydrogen storage capacity necessitates exploration of light alloying elements including Mg and Al. Here, we employ density-functional theory to investigate the hydrogen desorption energetics of Ti0.325V0.275Zr0.125Nb0.275 alloy and the impact of doping with Mg and Al. Our analysis reveals that Mg and Al addition thermodynamically destabilize the Ti0.325V0.275Zr0.125Nb0.275-hydride and lower its storage capacity. The observed destabilization is attributed to reduced chemical contributions to the desorption enthalpy in the Mg and Al-doped hydrides. Detailed examination of the electronic density of states, electron localization function, and crystal orbital Hamilton population analysis unveils fundamental features of chemical bonding in these hydrides. Notably, H-H antibonding states occur for hydrogen atoms located in the nearest-neighbor interstices of Mg and Al atoms. Charge transfer facilitates formation of these antibonding states. This comprehensive analysis enhances our understanding of the intricate interplay between electronic structure, hydrogen desorption energetics, and chemical bonding in HEA hydrides, offering valuable insights for the design and optimization of advanced hydrogen storage materials.

Due to their versatile composition and customizable properties, A2BC Heusler alloys have found applications in magnetic refrigeration, magnetic shape memory effects, permanent magnets, and spintronic devices. The discovery of all-d-metal Heusler alloys with improved mechanical properties compared to those containing main group elements presents an opportunity to engineer Heusler alloys for energy-related applications. Using high-throughput density-functional theory calculations, we screened magnetic all-d-metal Heusler compounds and identified 686 (meta)stable compounds. Our detailed analysis revealed that the inverse Heusler structure is preferred when the electronegativity difference between the A and B/C atoms is small, contrary to conventional Heusler alloys. Additionally, our calculations of Pugh ratios and Cauchy pressures demonstrated that ductile and metallic bonding are widespread in all-d-metal Heuslers, supporting their enhanced mechanical behavior. We identified 49 compounds with a double-well energy surface based on Bain path calculations and magnetic ground states, indicating their potential as candidates for magnetocaloric and shape memory applications. Furthermore, by calculating the free energies, we propose that 11 compounds exhibit structural phase transitions and suggest isostructural substitutions to enhance the magnetocaloric effect.

Solid-state magnetic refrigeration, based on the magnetocaloric effect, is a promising, highly energy-efficient, and environmentally friendly cooling technology. High-entropy metallic glasses (HE-MGs) have attracted increasing interests due to their excellent magneto-caloric properties across a wide temperature range. In this work, we successfully prepared three rare-earth (RE) based HE-MGs microwires and investigated their structural and magnetocaloric properties. The Gd25Dy25Co25Al25, Tb20Gd20Dy20Co20Al20, and Ho20Gd20Dy20Co20Al20 microwires exhibit an amorphous structure with good glass forming ability. They undergo a second-order phase transition from ferromagnetic to paramagnetic states around Curie temperatures of ∼61 K, ∼63 K, and ∼ 47 K, respectively. The peak magnetic entropy change (-ΔSM) for these HE-MGs microwires range from 8.2 J kg−1 K−1 to 10.2 J kg−1 K−1 under a 5 T magnetic field change. Furthermore, the refrigeration capacities of these microwires are evaluated to be between 504 J kg−1 and 507 J kg−1 (5 T), demonstrating their exceptional cooling efficiency. Additionally, this study provides valuable insights for the further research and development of RE-containing HE-MGs, paying the way for optimized materials tailored for advanced magnetic refrigeration applications.

Multi-component alloys have received increasing interest for functional applications in recent years. Here, we explore the magnetocaloric response for Al-Cr-Mn-Co medium-entropy alloys by integrated theoretical and experimental methods. Under the guidance of thermodynamic and ab initio calculations, a dual-phase system with large magnetic moment, i.e., Al₅₀Cr₁₉Mn₁₉Co₁₂, is synthesized, and the structural and magnetocaloric properties are confirmed via characterization. The obtained results indicate that the selected alloy exhibits a co-continuous mixture of a disordered body-centered cubic and an ordered B2 phase. The ab initio and Monte Carlo calculations indicate that the presence of the ordered B2 phase is responsible for the substantial magnetocaloric effect. The magnetization measurements demonstrated that this alloy undergoes a second-order magnetic transition with the Curie temperature of ∼300 K. The magnetocaloric properties are examined using magnetic entropy change, refrigeration capacity, and adiabatic temperature change. The property-directed strategy explored here is intended to contribute to the study of potential multi-component alloys in magnetocaloric applications.