Sintering process in hot oscillatory pressure of 90W–7Ni–3Fe refractory alloy at different time

Abstract 90W–7Ni–3Fe refractory alloys were prepared by hot oscillating pressure (HOP) and hot pressuring (HP) under vacuum condition at different sintering time. Density, grain size and hardness of pure samples were measured to interpret the influence of sintering time on sintering process. Because of the increasing sintering time, the influence of sintering temperature and oscillating pressure was extended. In a shorter sintering time (about 1h), the densification rate was higher, the density increased fast, the grain growth was not obvious, and higher hardness was obtained. When the sintering time was longer (more than 1h), the densification rate was significantly reduced, and little improvement on density. At this process, the grain size was significantly increased, resulting in a decrease on hardness. However, though vacuum conditions avoid impurity elements, the measurement shows that above of HOP sample was always better than that of HP at a set value of sintering time. Whatever, these results demonstrated that HOP is a better technology to sintering refractory alloys compared with HP.