Formation mechanism of interdiffusion layer and mechanical properties of Al0.6CoCrFeNi high-entropy alloy/Ti composites

Abstract

The 10 vol% Al0.6CoCrFeNi high entropy alloy (HEA) particles reinforced titanium matrix composites were fabricated successfully by hot pressing sintering under vacuum. The formation mechanism of interdiffusion layer and mechanical properties of the composites were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), back scattered electron (BSE), electron backscatter diffraction (EBSD) and compressive test. The results show that the interdiffusion layers composed of AlNi2Ti (BCC) and Ni-Ti mixed phases (FCC) are formed between the HEA particles and the matrix. The recrystallization mechanism of the composites is continuous dynamic recrystallization and second phase particle induced recrystallization. The concentration gradient and mixing enthalpy were the main driving force for the formation of phase in interdiffusion layer. The formation sequence of Ni-Ti mixed phases is NiTi2, NiTi and Ni3Ti. The compressive strength (1642 MPa) of the composites with the same strain (21.7%) is 86.1% higher than that of the pure titanium samples (882.5 MPa). During the compression process, cracking occurs at the Ni-Ti mixed phases interdiffusion layer.