Structural and hydriding properties of (Mg1-xCax)Ni-2 Laves phase alloys

Novel Mg-based pseudo-binary alloys (Mg1-xCax)Ni-2 which desorb hydrogen at room temperature were successfully developed. The alloys can be synthesize d by a conventional melting method and annealing technique. The crystal str ucture of annealed (Mg1-xCax)Ni-2 (0.32 less than or equal tox less than or equal to1.0) was the C15 Laves phase type and in this composition range th e alloys were single phase. Flat plateaus in the pressure-composition isoth erms were observed at ambient temperatures. The maximum hydrogen content of the present study is 1.4 mass% (H/M approximate to0.7) under hydrogen pres sure of 3.5 MPa at 313 K. The effects of substitution of Ca for Mg on the l attice parameter, hydrogen equilibrium pressure and phase changes with hydr ogenation are discussed. (C) 2001 Elsevier Science B.V. All rights reserved .