Abstract:Mg₂Ni_0.7M_0.3 (M=Al, Mn and Ti) alloys were prepared by solid phase sintering process. The phases and microstructure of the alloys were systematically characterized by XRD, SEM and STEM. It was found that Mg₃MNi₂ intermetallic compounds formed in Mg₂Ni_0.7M_0.3 alloys and coexisted with Mg and Mg₂Ni, and that radius of M atoms closer to that of Mg atom was more beneficial to the formation of Mg₃MNi₂. The hydrogen storage properties and corrosion resistance of Mg₂Ni_0.7M_0.3 alloys were investigated through Sievert and Tafel methods. Mg₂Ni_0.7M_0.3 alloys exhibited remarkably improved hydrogen absorption and desorption properties. Significantly reduced apparent dehydriding activation energy values of -46.12, -59.16 and -73.15 kJ/mol were achieved for Mg₂Ni_0.7Al_0.3, Mg₂Ni_0.7Mn_0.3 and Mg₂Ni_0.7Ti_0.3 alloys, respectively. The corrosion potential of Mg₂Ni_0.7M_0.3 alloys shifted to the positive position compared with Mg₂Ni alloy, e.g. there was a corrosion potential difference of 0.110 V between Mg₂Ni_0.7Al_0.3 alloy (-0.529 V) and Mg₂Ni (-0.639 V), showing improved anti-corrosion properties by the addition of Al, Mn and Ti.

Key words: Mg₂Ni; Mg₃MNi₂; hydriding kinetics; dehydriding activation energy; anti-corrosion properties