Increasing Amplitude at Low Temperatures to Obtain 90W–7Ni–3Fe Refractory Alloy with Excellent Corrosion Resistance Prepared by Hot Oscillatory Pressing

Abstract

90W–7Ni–3Fe refractory alloy with high density and excellent corrosion resistance was obtained for the first time by hot oscillating pressure (HOP) under different oscillating amplitudes (5, 10, and 15 MPa) at low temperatures (1000°C). As the amplitude increased, the 15 MPa sintered sample reached the maximum density of 99.4% with an average grain size of 3.41 μm by min-grain growth rate (about two-thirds of 5 MPa sintered sample), and the max-Vickers hardness reached 462.3 HV_0.5. The sintering curve was changed gently and presented full density at the end of the isothermal holding period. More importantly, the corrosion current density i_corr was reduced by nearly 1.07 times, and the corrosion resistance of 15 MPa samples was better than that of 5 MPa and 10 MPa samples and similar materials ever reported. The results show that the increase of amplitude is beneficial to the densification of refractory tungsten alloy and has a positive effect on improving the density, hardness, corrosion resistance and inhibiting the growth of grain size (the retention of the fine-grained microstructure) at low temperatures.