Preparation and Characterization of Amorphous W–B–C Alloy and Solid Solutions of C in Tungsten Borides

Abstract

Mixtures of W and B13C2 powders were mechanically milled and subsequently annealed at 900–1200 °C. It is found that amorphous W–B–C alloy formed as the mixtures were milled for 20–80 h. After annealing the 80 h-milled mixtures at 900–950 °C, solid solutions of C and/or B in tungsten [W(B, C)], C in tungsten boride [W2B(C) or WB(C)] formed by the crystallization of amorphous W–B–C. The formation temperature of W2B(C) and WB(C) is lower than that of W2B and WB reported previously. As the 80 h-milled mixtures were annealed at 1200 °C, W reacted with amorphous W–B–C completely to form WB and W2B5 or W2B5 instead of the solid solutions of C in tungsten borides, which is determined by the mole ratio of W to B13C2. The formation mechanisms of the W2B(C) and WB(C) solid solutions as well as phase transition rules of the mixtures at annealing temperature and mole ratio were also investigated using first-principle calculation.