High-entropy alloys (HEAs) are emerging as a hot research frontier in the metallic materials field. The study on the effect of alloying elements on the structure and properties of HEAs may contribute to the progress of the research and accelerate the application in actual production. FeCoCrNiAlTi_x (x = 0, 0.25, 0.5, 0.75, and 1 in at.%, respectively) HEA coatings with different Ti concentrations were produced on Q235 steel via laser cladding. The constituent phases, microstructure, hardness, and wear resistance of the coatings were investigated by XRD, SEM, microhardness tester and friction-wear tester, respectively. The results show that the structure of the coating is a eutectic microstructure of FCC and BCC₁ at x = 0. The structure of coatings consists of both proeutectic FCC phase and the eutectic structure of BCC₁ and BCC₂. With the continuous addition of Ti, the amount of eutectic structure decreases. The average hardness of the FeCoCrNiAlTi_x HEA coatings at x = 0, 0.25, 0.5, 0.75, and 1 are 432.73 HV, 548.81 HV, 651.03 HV, 769.20 HV, and 966.29 HV, respectively. The hardness of coatings increases with the addition of Ti, where the maximum hardness is achieved for the HEA at x = 1. The wear resistance of the HEA coatings is enhanced with the addition of Ti, and the main worn mechanism is abrasive wear.

This work investigates the mechanisms of the microstructure evolution in the melted surface layers of a WC-6% Co hard alloy when increasing the number of pulses of irradiation by high-current pulsed electron beam (HCPEB) treatment. After one pulse of irradiation, about 50% of the stable hcp WC phase was melted and resolidified into the metastable fcc form (WC_1−x). When increasing the numbers of pulse irradiation, the WC phase decomposed into ultrafine-grained WC_1−x plus nanosized graphite under our selected energy condition. Because of the rapidity of HCPEB carried under vacuum, the formation of the brittle W₂C phase was avoided. In the initial Co-rich areas, where the Co was evaporated, melting and solidification led to the formation of nanostructures Co₃W₉C₄ and Co₃W₃C. The volume fraction of the nano domains containing WC_1−x, Co₃W₉C₄, and Co₃W₃C phases reached its maximum after 20 pulses of irradiation. The improved properties after 20 pulses are therefore due to the presence of nano graphite that served as lubricant and dramatically decreased the friction coefficient, while the ultrafine-grained carbides and the nano domains contribute to the improvement of the surface microhardness and wear resistance.

Nickel chromium (NiCr) powders with different titanium diboride (TiB₂) additions (20, 40 and 60 wt %) were prepared with a mechanical alloying method and then sprayed using an air plasma spraying technology. The microstructure and phase composite of the powders and the cross-sections of deposited coatings were analyzed with a scanning electronic microscope and X-ray diffraction. The tribological performance of the coatings was studied using a pin-on-disk tribometer at room temperature. The weight loss of the as-sprayed coating was measured by using a high accuracy weighing balance. Cr₃C₂-25NiCr coating was produced and tested for comparison. The morphologies of the worn surface were then investigated. Parts of debris with some scratches were found, presenting typical signs of abrasive wear and showing slight adhesive wear on the surface. The 20 wt % additive TiB₂ coating demonstrated the highest microhardness and the lowest coefficient of friction. The wear resistance of the metal-ceramic composites coatings was enhanced with the addition of TiB₂.

The NiCr–TiB₂–ZrB₂ composite coating was deposited on the surface of blades made of steel (SUS304) using high-energy ball milling technology and air plasma spraying technology, which aimed to relieve the wear of the blades during operation. The influence of titanium diboride (TiB₂) and zirconium diboride (ZrB₂) on the microstructure and wear resistance of the coatings was investigated by X-ray diffraction, scanning electron microscopy, Vickers microhardness tester, and a wear tester. The results showed that the TiB₂ and ZrB₂ particles were unevenly distributed in the coatings and significantly increased the hardness and anti-wear, which contributed to their ultra-high hardness and extremely strong ability to resist deformation. The performance of the coatings was improved with the increase of the number of ceramic phases, while the hardness and wear resistance of the coating could reach their highest value when the TiB₂ and ZrB₂ respectively took up 15 wt.% of the total mass of the powder.

The ECAP (equal channel angular pressing) technique plays a crucial role in enhancing the overall performance of aluminum alloys. In this study, ECAP was applied to a self-developed micro-alloyed Al-0.7Fe-0.4Mg-0.1Si-0.5Er aluminum alloy to investigate the strengthening effects of varying numbers of passes. The results show that after four ECAP passes, the alloy achieved a high tensile strength (208 MPa), yield strength (175.4 MPa), elongation after fracture (10.8%), and a relatively high electrical conductivity (57.1%IACS). The enhanced strength is primarily attributed to precipitation strengthening (${\sigma }_p$), grain refinement strengthening (${\sigma }_{gbs}$), and dislocation strengthening (${\sigma }_{dis}$). The grain refinement is a result of dynamic recrystallization (DRX) induced by severe plastic deformation. This study demonstrates that ECAP enables a significant improvement in the mechanical properties (82.3%) of the alloy while causing only a marginal reduction (2.9%) in electrical conductivity. These findings provide both technological and theoretical support for the manufacturing of high-performance conductors and other lightweight electrical structural components.