Effect of Heat Treatment Temperature on Microstructure and Mechanical Properties of Co-Cr-W Alloy

Abstract

Co-Cr-W alloy was prepared by powder metallurgy technology. The effect of heat treatment temperature on the microstructure and mechanical properties of the prepared alloy was investigated by SEM and EPMA, etc. The results show that the phases in Co-Cr-W alloy under the heat treatment condition of 1100 ℃ with holding time of 4 h and cooling without power is the same as before heat treatment. The matrix of alloy is composed of γ-Co with FCC structure, ε-Co with HCP structure, and the reinforced phases include M6C and M23C6 carbides. The matrix of Co-Cr-W alloy under the heat treatment condition of 1150-1250 ℃ × 4 h is composed of single γ-Co in FCC structure and reinforced phases include M6C carbides and M23C6 carbides. When the heat treatment temperature is increased from 1100 ℃ to 1200 ℃, the blocky M6C carbides and granular M23C6 carbides grow up, meanwhile ε-Co phases are reduced and then disappeared, alloy density is improved, and tensile strength is increased. However, when the heat treatment temperature is above 1200 ℃, the performance of Co-Cr-W alloy has no obvious change, and the prepared alloy under the heat treatment condition of 1200 ℃ × 4 h achieves the optimal property with the average hardness of 63.5HRC and tensile strength of 408 MPa.

Keywords

• Co-Cr-W alloy
• heat treatment temperature
• microstructure
• mechanical property