Reactive synthesis and phase evolution of W(2)FeB(2) alloy powders

Using industrial FeB, tungsten powder, and amorphous boron powder as raw materials, W(2)FeB(2) alloy powder was successfully prepared by reaction synthesis. The reaction mechanism was analyzed by comparing the phase compositions of the alloy powder at different temperatures and holding times. The crystal structure of the W(2)FeB(2) phase in the alloy powder was studied, and the content of each phase in the powder was analyzed by the density of the alloy powder. The results showed that the density of the powder obtained at 1150 °C for 3 h reached 14.32 g cm(−3), and the alloy powder was composed of 93.42wt% W(2)FeB(2) phase with orthogonal structure and 6.58wt% W(2)B phase. The reaction synthesis process involved the diffusion of B atoms and Fe atoms into the W matrix, firstly forming binary phases such as WB, W(2)B, Fe(2)B, W(x)Fe(y), and then generating ternary phases W(x)Fe(y)B(z), and finally forming W(2)FeB(2) phase. The powder morphology was optimized by plasma spheroidization, and the fluidity of the powders increased with the decrease of the powder feeding rate. The powder flow rate reached 19 s/50 g with a 3 g min(−1) powder feeding rate. Metastable phases such as (Fe(0.6)W(2.8))B(4) and W(3.5)Fe(2.5)B(4) appeared after plasma spheroidization, but the phases could be eliminated with 1150 °C – 3 h annealing process.