Based on the excellent comprehensive mechanical properties of high–entropy alloy (HEA), the NiAl-based HEA was designed to achieve excellent high-temperature strength, toughness, and wear resistance. In this work, vacuum arc melting technology was used to prepare (NiA1)₇₈(CoCrFe)_16.5Cu_5.5 HEA, and its microstructure, phase composition, and mechanical properties were systematically studied. The results showed that (NiA1)₇₈(CoCrFe)_16.5Cu_5.5 HEA was composed of FCC and BCC/B2, with a spinodal decomposition structure in the matrix, and nano-precipitation in the interdendritic, exhibiting a good high-temperature performance. At 600 °C, the compressive fracture strength is 842.5 MPa and the fracture strain is 24.5%. When the temperature reaches 800 °C, even if the strain reaches 50%, the alloy will not fracture, and the stress–strain curve shows typical work hardening and softening characteristics. The wear coefficient of the alloy first increases and then decreases with the increase in temperature in the range of room temperature to 400 °C. However, the specific wear rate shows the opposite trend. At 100 °C, the wear rate reaches the lowest of 7.05 × 10⁻⁵ mm³/Nm, and the wear mechanism is mainly abrasive wear.

The effects of Sn and Mo alloying elements on the microstructure and electrochemical properties of TiZrTaNb high entropy alloys were studied by optical microscope (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemistry. TiZrTaNb, TiZrTaNbMo and TiZrTaNbSn alloys with equal atomic ratio were prepared by the arc melting method. The results showed that the microstructure of the high entropy alloys was dendritic structure with single BCC structure. The addition of Mo and Sn elements promoted the growth of the dendritic structure and accelerated the interdendritic segregation of the TiZrTaNb alloy. The TiZrTaNbMo alloy exhibited excellent corrosion properties compared to TiZrTaNb and TiZrTaNbSn alloys based on corrosion parameters I_corr, φ_corr, I_pass. The corrosion mechanism is discussed based on the corrosion morphology. The alloying elements have an important effect on the microstructure and electrochemical properties of a high entropy alloy.

To refine the grain size and improve the mechanical properties of ultrahigh-strength aluminum alloy (Al-10Zn-1.9Mg-1.6Cu-0.12Zr), the Al-Ti-B-Er grain refiner was prepared by the melt reaction method using the aluminum melt and Al + Ti + B precursor. The results exhibit that the Al-Ti-B-Er grain refiner is mainly composed of a block TiAl₃ phase, and loose agglomerated nano-sized TiB₂ and Al₃Er phases. The microstructure of ultrahigh-strength aluminum is significantly affected by the Al-Ti-B-Er refiner, which changes from dendrite to equiaxial grain with increasing Al-Ti-B-Er content, and the size of the eutectic phase is significantly refined. The high-efficiency refinement of Al-Ti-B-Er is due to Er promoting the uniform distribution of TiAl₃ particles and the formation of loose agglomerated nano-sized TiB₂ particles. The optimal addition content of Al-Ti-B-Er into ultrahigh-strength aluminum alloys is 1 wt%, whose grain size is approximately 40 µm. Additionally, the strength and ductility of ultrahigh-strength aluminum alloys are simultaneously improved by adding 1wt% Al-Ti-B-Er after the T6 treatment, reaching 756 MPa and 20%, respectively. This enhancement in strength and ductility is mainly attributed to grain refinement and the eutectic phase refinement.