Hydride–Dehydride Processes and Behaviors for Ductile Refractory Complex Concentrated Alloys

To find an effective method for preparing low-H/O impurity pollution powders of refractory complex concentrated alloys (RCCAs) with decent plasticity levels, the hydride–dehydride process and behavior characteristics of Ti 2 ZrTa 0.75 RCCA were investigated. After the hydrogenation process at a temperature of 600°C and a hydrogen pressure of 0.2 MPa for a time of 2 h, Ti 2 ZrTa 0.75 RCCA transformed into M 3 H 2 metal hydrides with hydrogen concentrations of 0.61 wt.% and then hydrogen-induced fragmentation. Meanwhile, fragmentary RCCAs have a low impurity oxygen content (0.0545 wt.%). Then, nearly spherical powders with average particle sizes of 4.5 μ m were obtained by ball milling for 4 h. Finally, the dehydrogenation process at 450°C for 2 h reduced the hydrogen concentration in the Ti 2 ZrTa 0.75 RCCA powder to 0.0074 wt.%, while the near-spherical shape and small particle size ( D 50 = 9.4 μ m) were maintained, with the near-spherical shaped RCCA powders with BCC + HCP dual-phase structures. By fitting the hydrogenation and dehydrogenation kinetics curves, the hydrogenation and dehydrogenation behaviors of Ti 2 ZrTa 0.75 RCCA were mainly controlled by the diffusion of hydrogen atoms. The results of this work proved that spherical Ti 2 ZrTa 0.75 RCCA powder with low-H/O impurity pollution and a small size could be successfully prepared by the hydride–dehydride method. The hydride–dehydride method was thus an effective method for preparing low-H/O impurity pollution powder composed of RCCAs with decent plasticity levels.