Hydrogenation Behavior in Ti-Cr Alloys with Compositions around TiCr₂ Laves Phase

Abstract

Hydrogenation behavior in Ti–Cr alloys with compositions around TiCr₂ Laves phase has been examined by the tritium radioluminography and the PCT measurement. All of the specimens have been two-phase structure of BCC phase and Laves phase. The ratio of the BCC phase to the Laves phase has been increased as increasing the heat treatment temperature. The Ti-rich BCC phase and Cr-rich BCC phase have been formed in the Ti₅₀Cr₅₀ alloy and the Ti₃₀Cr₇₀ alloy, respectively. It is found that hydrogen easily penetrates into the Laves phase in the initial stage of hydrogen penetration. In the PCT measurements, Ti₅₀Cr₅₀ alloy absorbed the largest amount of hydrogen. The maximum protium storaging capacity of 3.5 mass% was obtained in the Ti₅₀Cr₅₀ specimen heat treated at 1400°C at the measured temperature of 150°C. The plateau of PCT curves in Ti₅₀Cr₅₀ alloy and Ti₃₀Cr₇₀ alloy appeared at low hydrogen pressure and high hydrogen pressure region, respectively. These plateaus are attributed to the Ti-rich BCC phase and the Cr-rich BCC phase, respectively.