Hot oscillatory pressure sintered W–Ni–Fe refractory alloy under different sintering pressures: Microstructures, densification behavior and properties

Abstract

The 90 W–7Ni–3Fe refractory alloy (in mass %) was firstly sintered and obtained by hot oscillatory pressure (HOP) at different sintering pressures under vacuum conditions without oxygen and hydrogen pollution in this work. The HOPed alloys contained the two-phase composition: W phase and γ-Ni(Fe) binding phase. It significantly improved the microstructure uniformity as sintering pressure increased. And the higher oscillatory pressure could significantly contribute to getting the faster densification rate and shortening the sintering time. Its highest density and smallest grain size in the HOP-40 sample (at the highest sintering pressure of 40 MPa) were about 99.5% and 3.78 μm, respectively. In addition, the large number of dislocation lines and dislocation arrays that appeared in the higher sintering pressure sample also confirmed the plastic deformation mechanism. The Vickers hardness of the HOP-40 sample could be reached at the highest level of 447.8 HV0.5, while its corrosion current density icoor was only about 2.1✕10−6 A/cm2. In brief, the sintering pressure increasing has a positive effect on HOPed W–Ni–Fe refractory alloys to promote faster densification, suppressing grain size, leading dislocation strengthening, and enhancing hardness and corrosion resistance.