Structural-Phase State and Microhardness of a Precursor from Equiatomic W-Ta-Mo-Nb-Zr-Cr-Ti Powder Mixture after High-Energy Mechanical Activation

Abstract

This study explores how the time of high-energy mechanical activation affects the structuralphase state and microhardness of a multicomponent W-Ta-Mo-Nb-Zr-Cr-Ti powder mixture of equiatomic composition. It was found that, in the precursor thus formed, micron-sized particles are fragmented and the degree of consolidation of large agglomerates increases, while the morphology of the agglomerates remains almost unchanged. In addition to the main bcc phase with nearly equiatomic composition W 13-16 Ta 14-17 Mo 11-15 Nb 11-16 Zr 11-15 Cr 13-18 Ti 14-16 , secondary bcc phases based on Ta and W are formed in the precursor. Mixing of these phases during mechanical activation promotes the gradual transition of the precursor to a single-phase state represented by the main bcc phase. These processes in the conditions of high-energy mechanical activation are shown to be activated and enhanced at much shorter times than during lower-energy mechanical activation. It is supposed that the formation of a nearly single-phase state, along with an increasing degree of consolidation of the powder mixture, contributes to an increase in the microhardness of the obtained precursor in contrast to a decrease in the average deviation H V .