The effects of oscillating frequency on microstructure and hardness of W‐Ni‐Fe refractory alloy sintered by hot oscillating pressure

90 W‐7Ni‐3Fe refractory alloys are first sintered by hot oscillating pressure (HOP) under different oscillating frequencies (0, 1, and 10 Hz) in this work. The effects of oscillating frequencies on the microstructure and Vickers hardness are investigated. With the oscillating frequency increasing, the relative density and hardness of refractory alloys are obviously improved. Especially, the alloy sintered at the oscillating frequency of 10 Hz had the highest relative density of approximately 98.9% and the smallest average grain size of 3.26 μm. Moreover, the narrowest average thickness of the bonding phase is about 0.18 μm, and the lowest tungsten contiguity is about 61.1%. Then its excellent hardness (456.8 HV 30 ) is obtained, which is nearly 16.1% higher than that of the 0 Hz frequency alloy. The refractory alloy with high densification, small grain size, and good hardness could be obtained by HOP with a high oscillating frequency.