Study of the structure and mechanical properties of nano- and ultradispersed mechanically activated heavy tungsten alloys

Abstract

Mechanisms of sintering and the structure and mechanical properties of nano- and ultradispersed W-Ni-Fe (WNF) and W-Ni-Fe-Co (WNFC) heavy tungsten alloys are investigated. The effect of tungsten particle sizes on the optimal sintering temperature is studied. The size of particles has been changed by the mechanical activation (MA) of the source W-Ni-Fe coarse-grained (CG) charge and by adding ultradispersed particles obtained using plasmochemical synthesis. Nanodispersed powders and ultradispersed powders (UDPs) have been sintered using the techniques of free sintering and pulse plasma sintering (PPS). It has been revealed that the dependence of the alloy density on heating temperature is nonmonotonic, with the maximum corresponding to the optimum sintering temperature. It has been shown that an increase in the time of MA and acceleration of grinding bodies in the process of MA accompanied by a decrease in the size of alloy particles and formation of nonequilibrium solid solutions lead to a reduction in the optimal sintering temperature. It has been shown that, using planetary high-energy milling methods and high-rate spark plasma sintering, it is possible to obtain ultrastrong tungsten alloys whose mechanical properties (macroelasticity stress and yield stress) substantially exceed analogous properties of commercial alloys.