Microstructures and Properties of 90W-10Cu Refractory Alloy Sintered Under Different Hot Oscillatory Pressure Sintering Temperature

Due to the differences in high melting point and specific gravity, the 90W–10Cu refractory alloy, used in high-voltage electrical contact materials, experiences challenges in densification and abnormal grain growth during the high-temperature, long-duration powder metallurgy process, affecting its properties. Based on conventional hot press sintering, the novel hot oscillatory pressure (HOP) technology enhances the densification of ceramics and other materials by substituting static uniaxial pressure with cyclic oscillatory uniaxial pressure at a specific frequency. In order to investigate the low-temperature sintering effects of HOP on the 90W–10Cu refractory alloy, this technology is applied to the alloy’s preparation, examining the impacts of varying sintering temperatures (1 000～1 300 °C) on its microstructure, densification, grain size, hardness, and electrical conductivity. The 90W–10Cu alloy comprises a W matrix phase and a bonding Cu phase. As the sintering temperature increases, the W–Cu alloy’s density gradually rises, reaching a peak density of nearly 99.35% at 1 300 °C, surpassing that of samples sintered under hot pressure (HP). The grain size is reduced to 4.97 μm, affecting grain refinement. Simultaneously, W grain contiguity decreases, enhancing microstructure uniformity. Consequently, its Vickers hardness and electrical conductivity reached 225.78 HV30 and 27.88% IACS, respectively, exceeding those of HP-sintered samples at the same temperature of +100 °C, thus considerably enhancing its properties. The findings indicated that HOP effectively promotes the densification of the W–Cu alloy at lower sintering temperatures, inhibits grain growth, and significantly optimizes microstructure uniformity. Therefore, the 90W–10Cu alloy for electrical contacts, characterized by high density, fine grain, and improved hardness and conductivity, can be achieved through HOP at low-temperature sintering. © 2024 Sichuan University. All rights reserved.