Spark Plasma Sintering Effect on Microstructure and Properties of CoCrCuFeNi High Entropy Alloy

Abstract:

In this paper, CoCrCuFeNi high-entropy alloy was successfully fabricated by spark plasma sintering (SPS) at 900 oC, 1000 oC, 1100 oC and 1150 oC. The tensile at room temperature results shows that the tensile strength of the CoCrCuFeNi alloy firstly decreases and then increase with the increase of sintering temperature. However, the uniform elongation firstly significantly increases and then decreases. When the sintering was carried out at 1100 oC, the yield strength and unltimate tensile strength of CoCrCuFeNi alloy reaches 379.3 MPa and 655.6 MPa, respectively, and the elongation after fracture is 21.9%. When sintering temperature above 1100 oC, the element segregation obviously appears in the material because of the local melting. Besides, the tensile fracture is brittle feature along the surface of the spherical powder at 900℃. While the fracture is a ductile fracture as the sintering temperature increases. Because of the diffusion of carbon atom during high temperature sintering, TEM results show that the carbon reacts with the matrix to form second phase carbide particles inside the matrix.

Key words:High-entropy alloy; spark plasma sintering; mechanical properties; sintering temperature