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 Ti2ZrTa0.75 RCCA were investigated. After the hydrogenation process at a temperature of 600 degrees C and a hydrogen pressure of 0.2 MPa for a time of 2 h, Ti2ZrTa0.75 RCCA transformed into M3H2 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 mu m were obtained by ball milling for 4 h. Finally, the dehydrogenation process at 450 degrees C for 2 h reduced the hydrogen concentration in the Ti2ZrTa0.75 RCCA powder to 0.0074 wt.%, while the near-spherical shape and small particle size (D50 = 9.4 mu 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 Ti2ZrTa0.75 RCCA were mainly controlled by the diffusion of hydrogen atoms. The results of this work proved that spherical Ti2ZrTa0.75 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.