Microstructure and properties of high entropy alloy reinforced titanium matrix composites

In this paper, CoCrFeNiMo0.2 high entropy alloy (HEA) particles reinforced titanium matrix composites were prepared by hot pressing sintering in the vacuum. The microstructure and composition of the composites at 700 °C ~ 900 °C were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Also, the mechanical properties of the composites were studied by microhardness tester, nano-indentation and uniaxial compression experiment. The results show that the interface layer of different thicknesses is formed between the particles and the matrix in the composites under different sintering temperatures. At 700 °C ~ 850 °C, the mechanical properties of the composites increase with the increase of temperature, which is related to the diffusion of HEA particles and the formation of the interface layer. When the sintering temperature is 850 °C, the hardness is 402.6 HV, the yield strength is 928.2 MPa, and the compressive strength is 2032.6 MPa. However, the high entropy alloy particles have a greater degree of dissolution and diffusion at 900 °C, the strengthening effect of the particles is weakened, so the mechanical properties of the composites are correspondingly reduced.