Laser cladding is an effective surface strengthening method widely used in the surface treatment of extreme operating components such as gas turbines, aviation engines, and nuclear facilities. However, traditional cladding layers struggle to meet the diverse application needs of extreme working conditions due to their single cladding material and poor forming quality. Therefore, this article selected the new-type high-entropy alloy as the coating material and optimized its laser cladding process parameters in order to obtain an AlCrFeNiW_0.2 high-entropy alloy coating with an excellent forming quality. It was found that as the laser power increased from 300 to 1800 W, the AlCrFeNiW_0.2 high-entropy alloy coating transitioned from the incomplete or near-melted state to the fully and over-melted state gradually, while the coating showed the opposite trend of change as the laser scanning speed increased from 0.002 to 0.008 m/s. And when the laser power was 1000 W, the scanning speed was 0.005 m/s, and the spot diameter was 0.003 m, the AlCrFeNiW_0.2 high-entropy alloy coating with a low dilution rate (9.95%) had no defects such as pores and cracks, and achieved good metallurgical bonding with Q235 steel substrate, demonstrating excellent forming quality. These could provide valuable theoretical and technical guidance for optimizing the laser cladding process and forming quality of new-type high-entropy alloy coatings.

The new-type CoCrFeNiMoTi_x high-entropy alloy coatings were successfully devised and prepared on Q235 steel using laser cladding. Influence of Ti content on their microstructure and wear-resistance was studied systematically; the relevant mechanisms were deeply revealed. The CoCrFeNiMoTi_x coatings consisted of NiTi, FCC, and BCC phases, and with the increasing of Ti content, contents of BCC phase and FCC phase gradually increased and decreased, respectively. The CoCrFeNiMoTi₀.₇₅ coating had the highest hardness (950 HV), which was about 6.5 times higher than the substrate (Q235 steel, 150 HV). According to Archard law, metal materials’ wear resistance is generally proportional to hardness; thus, the CoCrFeNiMoTi₀.₇₅ high entropy alloy coating with the highest hardness showed the best wear resistance, exhibiting a wear mechanism of slight abrasive wear.

The CoCrFeNi₂Mo_x (x = 0, 0.4, 0.5, 1.0, x values in atomic ratio) high-entropy alloy coatings were designed and prepared on the Ti-6Al-4V substrate by laser cladding technology, their microstructures, and dry sliding wear resistance were studied in detail. When x < 0.4, the coatings were mainly composed of BCC solid solution phase, (Ni, Co)Ti₂ phase, and α-Ti phase. When x ≥ 0.4, the new σ phase appeared in the coatings. As the Mo content increases from 0 to 1.0, the hardness showed a trend of first increasing and then decreasing, especially when x = 0.5, the coating hardness reached its maximum (882 HV), which was 2.65 times the hardness of the Ti-6Al-4V substrate. The CoCrFeNi₂Mo_x high-entropy alloy coatings significantly improved the wear resistance of Ti-6Al-4V substrate, and with the increase in Mo content, the friction coefficient, widths/depths of worn tracks and wear rates of the coatings showed a trend of first decreasing and then increasing. In particular, when x = 0.5, the CoCrFeNi₂Mo_0.5 high-entropy alloy coating has the lowest friction coefficient (0.63), widths/depths of worn tracks (width: 803.690 μm; depth: 20.630 μm) and wear rate (5.136 × 10⁻⁵ mm³/(N·m)), which is one order of magnitude smaller than that of the substrate (3.694 × 10⁻⁴ mm³/(N·m)), demonstrating the best wear resistance. This is mainly because the appropriate proportion of hard α-Ti and σ phases effectively played a supporting role in resisting wear, while the relatively soft and dispersed BCC and (Ni, Co)Ti₂ phases could effectively prevent the occurrence of brittle fracture during wear test process.

Al_0.6CoFeNi₂V_0.5 high entropy alloy was successfully designed and prepared via the nonconsumable arc-melting process, and it was annealed at 600 °C, 800 °C, and 1000 °C for 4 h. Its microstructure and mechanical properties were studied. The as-cast alloy consisted of FCC and BCC phases, and no phase transformation occurred during annealing at 600 °C. Hard Al₃V-type metal compounds precipitated during annealing at 800 °C, and BCC particles precipitated in the FCC matrix during annealing at 1000 °C. After annealing, the strength and hardness of Al_0.6CoFeNi₂V_0.5 high-entropy alloy both showed a decreasing trend, because the annealing process eliminated the internal stress in this alloy. However, as the annealing temperature increased, the strength and hardness of the Al_0.6CoFeNi₂V_0.5 high-entropy alloy samples gradually increased. This is because the hard Al₃V metal compounds precipitated when the annealing temperature was 800 °C, which produced the “second phase strengthening” effect. At 1000 °C, the larger volume fraction of the hard and fine BCC phase (21.81%) diffusely precipitated; the precipitation of this BCC phase not only produced a “second phase strengthening” effect, which also resulted in “solid solution strengthening”, ultimately exhibiting enhanced hardness and strength. These findings have important theoretical reference value for the study of the microstructure and mechanical properties of high-entropy alloys. And, this study plays a significant role in promoting the research and development of new component materials that bear compressive loads, such as columns in large factory buildings, supports for cranes, and clamping bolts for rolling mills in practical mechanical engineering.

Al_0.2CoCrFeNi-5%WC high-entropy alloy (HEA) composites were fabricated via spark plasma sintering at temperatures ranging from 900 °C to 1050 °C, and the effects of sintering temperature on phase constitution, microstructure, and mechanical properties were systematically investigated. The results show that all composites consist predominantly of an FCC matrix, WC, M₂₃C₆ and M₆C carbides. With increasing sintering temperature, interfacial reactions are promoted, leading to the progressive consumption of WC and an increase in carbide content. The composite sintered at 1000 °C achieves the optimal combination of properties, with a relative density of 96.8%, a yield strength of 468 MPa, an ultimate compressive strength of 1871 MPa, and a fracture strain of 43.6%. The outstanding strength–ductility synergy originates from near-full densification, robust interfacial bonding, and multiple carbide strengthening mechanisms. Excessively high sintering temperature (1050 °C) results in reinforcement coarsening and degradation of mechanical properties.