Sintering densification,microstructure and properties of W-CoCrNi alloy
In this paper,high-density tungsten alloys with CoCrNi medium entropy alloy as bonding phase were prepared by powder metallurgy technology.The effects of bonding phase content and sintering temperature(1300-1500℃)on the microstructures and mechanical properties of the alloy were investigated.The results show that the sintered alloy are mainly composed of W phase,CoCrNi solid solution phase,Co7W6 phase and Cr-rich submicron particles.The relative density of the alloy decreases with the increase of sintering temperature.The densification mechanism of the alloy sintered below 1500℃is mainly solid-phase sintering mechanism,and the driving force of solid-phase sintering is mainly from the reduction of surface free energy and the formation of Co7W6 phase.When the sintering temperature reaches 1500℃,the densification mechanism is mainly liquid-phase sintering mechanism,and the densification process includes three stages:dissolution and diffusion of W to CoCrNi melt,Co7W6 phase precipitation and spheroidization of tungsten particles.The compressive yield strengths of 75W-CoCrNi and 95W-CoCrNi sintered at 1500℃are 1060 MPa and 1602 MPa,respectively,and the fracture of 75W-CoCrNi alloy does not occur when the compressive strain exceeds 50%.With the increase of CoCrNi binder phase content,the density of the alloy increases,the compressive deformation ability increases,whereas the compressive yield strength decreases.
CoCrNi medium entropy alloyhigh-density tungsten alloymicrostructuremechanical propertydensification
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NSTL
万方数据
维普
