This feature article summarizes the principles, fabrication techniques, and recent advancements of nanoporous high-entropy alloys and metallic glasses for application in electrochemical water splitting.

In the present study, FeCoCrNiAl _x (x = 0.3, 0.7) coatings were fabricated by laser cladding technology. XRD analysis and scanning electron microscopy (SEM) were used to investigate the evolution of phases and microstructures before and after the high-temperature oxidation test. The micro-hardness, tribological behaviour, and corrosion resistance of the coatings, before and after the high-temperature treatment, were systematically investigated using micro-hardness test, abrasive wear test, and electrochemical corrosion test. The microstructure and properties of FeCoCrNiAl_0.3 cladding layer changed little before and after the high-temperature oxidation test. The high-temperature condition promoted the generation of BCC solid solutions at the grain boundaries when the Al element content was 14.89% (i.e. 0.7 mol). This enhanced the micro-hardness and tribological behaviour, but deteriorated the corrosion resistance.

The long, straight grain boundary of the high-entropy alloy (HEA) produced via laser melting deposition (LMD) is prone to cracking due to unidirectional scanning (single wall). To enhance the competitive growth of columnar grains and improve the overall performance of the alloy, a vertical cross scanning method was employed to fabricate FeCoCrNi HEA (bulk). The influence of grain orientation on the microstructure and mechanical properties of FeCoCrNi-LMD was systematically investigated. Microhardness tests and tensile tests were conducted to assess the mechanical property differences between the single-wall and bulk samples. This study shows that using a single scanning strategy results in monolayer wall grains sized at 129.40 μm, with a max texture strength of 21.29. Employing orthogonal scanning yields 61.15 μm block-like grains with a max texture strength of 11.12. Dislocation densities are 1.084 × 10¹² m⁻² and 1.156 × 10¹² m⁻², with average Schmid factors of 0.471 and 0.416. In comparison to the FeCoCrNi-LMD single wall, the bulk material produced through cross-layer orthogonal scanning exhibited reduced residual stress, weakened anisotropy, and improved mechanical properties. These findings are expected to enhance the potential applications of FeCoCrNi-LMD in various industries.