Characteristics of hydrogen storage of as-milled TiFe-based alloys

Abstract

The phase structure, activation and kinetic performances of the as-cast and milled Ti1.04Fe0.6Ni0.1Zr0.1Mn0.2Sm0.06 alloys were investigated. The alloys contained TiFe, Ti2Fe and Sm segregation phases. Ball milling resulted in the occurrence of the particle pulverization and aggregation. It also introduced new crystal defects, disordered or amorphous structures in the alloys. The short-time ball milling can increase the activation property, shorten the incubation time and increase the hydrogenation capacity, whereas the long-time ball milling showed negative effects. The alloy milled for 0.5 h showed the optimum activation property and hydrogenation capacity. The activation began at 82 s and reached 1.713 wt% of hydrogenation capacity (423 K). The particle pulverization not only increased the contact surface between hydrogen molecules and the alloys but also increased the content of bare Sm segregation phase. Sm segregation phase provided the original power for the alloy pulverization, which also can be used as the specific diffusion channel of hydrogen atoms. The weakened performances of the alloy milled for 5 h were related to the particle aggregation and disordered or amorphous structures.