Structural and hydriding properties of (Mg 1− xCa x)Ni 2 Laves phase alloys

Abstract

Novel Mg-based pseudo-binary alloys (Mg 1− x Ca x )Ni 2 which desorb hydrogen at room temperature were successfully developed. The alloys can be synthesized by a conventional melting method and annealing technique. The crystal structure of annealed (Mg 1− x Ca x )Ni 2 (0.32≤ x≤1.0) was the C15 Laves phase type and in this composition range the alloys were single phase. Flat plateaus in the pressure–composition isotherms were observed at ambient temperatures. The maximum hydrogen content of the present study is 1.4 mass% (H/M≈0.7) under hydrogen pressure of 3.5 MPa at 313 K. The effects of substitution of Ca for Mg on the lattice parameter, hydrogen equilibrium pressure and phase changes with hydrogenation are discussed.