Formation of rhenium diboride via mechanochemical-annealing processing of Re and B

摘要

Rhenium diboride (ReB_2) powder was prepared by mechanochemical processing of Re-B powder mixtures with subsequent annealing at temperatures of 600 °C to 1200 °C. Reactive evolution during the synthesis was investigated;;furthermore, the effects of the amount of excess B on the reactions that occurred during the synthesis were assessed. The substantial reaction of Re with B occurred at 700 °C to form Re_7B_3 with a small amount of ReB_2. At 800 °C, Re_7B_3 converted into ReB_2; this conversion was enhanced with increasing temperature and increasing amount of excess B. At 1000 °C or above, single-phase ReB_2 powder without trace quantities of Re_7B_3 was obtained for compositions with 15 wt% or greater excess B. The synthesized ReB_2 powder particles were submicrometer with the vast majority being ~500 nm. In addition, the resulting ReB_2 powders were consolidated by hot pressing or spark plasma sintering to examine the sintcrability of the powders.