Studies towards activation of cobalt in W-Mo-Cu alloy sintered via large current electric field

Abstract

W-Mo-Cu alloy is a novel, potential pseudo-alloy but demand efficient and reliable manufacturing approaches. In this study, W-Mo-Cu alloys with (1–5 wt%) Co additives were fabricated using large current electric field sintering at a pressure of 25 MPa and a low temperature of 950 °C. The effects of Co on the microstructure and properties of the W-Mo-Cu alloys were investigated. The results revealed an activation effect of Co on W-Mo-Cu alloys. Increasing the Co content from 0 to 5 wt%, resulted in a substantial reduction of the calculated sintering activation energy by 69.6%, thereby enhancing the sinterability of W-Mo-Cu mixed powder and increasing the sintering densification degree of W-Mo-Cu alloy. During the sintering process, a large quantity of Co was enriched around the matrix particles and partially dissolved in the W, Cu, whereas a small number of matrix atoms dissolved into Co, which followed the classical activated sintering model. Moreover, an appropriate increase in the Co content was conducive to an optimal microstructure with increased sintering densification accompanied by increased hardness. However, the addition of Co adversely affected the electrical conductivity of W-Mo-Cu alloys.