HYDROGEN DESORPTION PROPERTIES OF THE QUATERNARY ALLOY SYSTEM MG(2-X)M1(X)NI(1-Y)M2(Y)

The effect of substitutions for Mg and Ni in the Mg2Ni alloy on hydrog enation properties was studied. In the case of substitution for Mg onl y, the desorption equilibrium pressure remained constant while the uni t cell volume changed. But in the quaternary alloy system obtained fro m Mg2Ni by simultaneous substitutions for Mg and Ni, the cell volume c orrelated with the hydrogen pressure. This is because hydrogen has a t endency to enter interstitial sites in the quaternary Mg2Ni based allo ys, the same behavior as found in the case of AB(5). Therefore, the hy drogenation properties of Mg2Ni will be improved by tailoring the effe ct of cell volume using suitable substitution elements. (C) 1998 Elsev ier Science S.A.