Abstract
In this study, different amounts of TaC powders (0, 10, 15 and 20 mass%) were mixed and added to the cobalt-based alloy powders. The composite powders were sintered at 1260, 1270, 1280 and 1290°C, respectively, for 1 h. The experimental results showed that adding 10 mass% TaC and sintering at 1270°C for 1 h was the optimal process, resulting a high TRS value of 1160 MPa and uniform carbides precipitations. From the microstructural observations, it was cleared that M6C carbides precipitated in the matrix of the Co-based alloys (0% TaC) after vacuum sintering. However, the more uniform precipitations of M6C, M23C6 and MC (M = Ta) carbides precipitated in the matrix and grain boundaries of the Co-based alloys after vacuum sintering. Furthermore, in the HIP treatment (1250°C/125 MPa/100 min) of 0% and 10% TaC sintered composite materials, it was proved that the closed pores were effectively eliminated and mechanical properties significantly improved. The highest hardness (HRA 79.3) and TRS (1720 MPa) were obtained by adding 10% TaC powders, which were sintered at 1270°C for 1 h, followed by HIP treatment.
