Research on Microstructure and High Temperature Mechanical Properties of Laser Melting Deposited AlNb_0.5CoCrNi₂ High Entropy Alloy

A new AlNb_0.5CoCrNi₂ high-entropy alloy was prepared by laser melting deposition technology, and the microstructure and high-temperature mechanical properties of the alloy were studied. The microstructure of the alloy was observed by X-ray diffraction(XRD), scanning electron microscope(SEM)and transmission electron microscope(TEM), and the high temperature tensile performance test was carried out for the sample at 760-1000 ℃. The results show that the microstructure of the alloy is composed of FCC phase, B2 phase and Laves phase, in which nanoscale L1₂ phase exists in FCC phase, and nanoscale A2 phase and nanoscale Laves phase exist in B2 phase.During the high-temperature stretching process, the strength of the alloy decreases and the plasticity increases as the temperature increases, and the alloy undergoes a brittle-ductile transition between 760-800℃. The best strength-toughness matching is exhibited for the alloy at 800℃, the deformation mechanism of the alloy at the temperature is mainly dominated by dislocations in the FCC matrix.