Effects of CuSn on the diamond particle holding force of pressureless sintered FeCuCo-based diamond tools

Abstract

Gas atomized FeCuCo (Cu 28.7 wt% Cu, 12.1 wt% Co) prealloyed powder was used as matrix of diamond tools, and CuSn (15. wt% Sn) prealloyed powder was used as sintering aids. The content of diamond particles was 0.35 wt%. The alloys were prepared through pressureless sintering. Effects of CuSn addition on mechanical properties, microstructure, and holding force of diamond particle were studied. The results show that the FeCuCo alloy is mainly composed of α-Fe phase and Cu-rich phase. Co and Sn are solid solution atoms of α-Fe phase and Cu-rich phase respectively. The fracture morphology of FeCuCo alloy mainly fine dimple and quasi cleavage fracture, as well as sintered pore surface and crack. With the increase of CuSn addition, the density, hardness, bending strength and diamond particle holding force of the alloy increase first and then decrease. The hardness, bending strength, and relative density of FeCuCo alloy with 8 wt% CuSn reach the peak. The bending strength of this alloy added with diamond particles reaches 871 MPa, and the strength loss rate is only 21.7%. There is an obvious gap between the diamond particles and the matrix, indicating that the holding mechanism is mainly mechanical encapsulation. After the addition of CuSn, there are more attachment on the surface of diamond particles, resulting in metallurgical bonding.