Effects of Carbon Nanotubes and Nickel-Plated Carbon Nanotubes on the Microstructure and Mechanical Properties of AlCoCrFeNiCu High Entropy Alloy

High entropy alloys AlCoCrFeNiCuCNTs(x) and AlCoCrFeNiCu(Ni-CNTs(x) (x = 0.2 wt%, 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%) were prepared by powder metallurgy. The effects of CNTs and nickel-plated CNTs content x on the microstructure and mechanical properties of the high entropy alloys were investigated by XRD, SEM, FESEM, Raman spectrum, hardness tests and compression tests. The results showed that the dispersion of nickel-plated CNTs in the alloy powder was obviously better than that of CNTs, and a large number of agglomerates will appear when the amount of CNTs and nickel-plated CNTs were too much. The defect degree of the high entropy alloy powder with Ni-CNTs(x) was higher than that of the high entropy alloy powder with CNTs(x). The high entropy alloys blocks with CNTs and nickel-plated CNTs were both BCC + FCC two-phase solid solution structures, and the micromorphology were composed of dendritic grains. Both CNTs and nickel-plated CNTs in appropriate amount refined grains, and nickel-plated CNTs had better grains refining effect. The hardness, compressive strength and compressive plasticity of high entropy alloys blocks first increased and then decreased with the increase of CNTs and nickel-plated CNTs, and reached the best value when the content was 0.5 wt%.