Abstract
The protium absorption-desorption properties of Ti–V–Cr–(Mn, Ni) alloys were investigated in conjunction with Mn, Ni and V contents and heat-treatment conditions. The compositions studied were (1) Ti–35V–(37–x)Cr–xM (M=Mn and Ni; 0≤x≤15), and (2) Ti–xV–Cr–M (M=Mn and Ni; 15≤x≤45) in which the content of Ti, Cr, and M was fixed at a ratio of 28:32:5. The addition of Ni reduced the protium storage capacity and increased the plateau pressure due to the formation of a Ti2Ni secondary phase, and to the incorporation of Mn into the BCC matrix phase. Increasing the V content was found to be an effective way of stabilizing the BCC phase, and thereby increasing the protium storage capacity. For Ti–V–Cr–Ni alloys, the slope of the plateau region was also improved by increasing the V content. In addition, the Mn-added alloy after annealing at 1573 K exhibited an almost uniform BCC solid solution and a storage capacity as high as 2.6 mass%; however, the Ni-added alloy still contained the Ti2Ni phase. The addition of Mn was found to be an effective way of decreasing the slope of the plateau region.
