Structure and related properties of (La,Ce,Nd,Pr)Ni-5 alloys

The effects of substitution of La by Ce, Nd and Pr in the LaNi5-based alloy s were systematically studied, with the use of factorial analysis. The chan ges of equilibrium pressure, hydrogen capacity and hysteresis were analyzed in relation to the structure changes of the hexagonal unit cell of (La,Ce, Nd,Pr)Ni,. Both individual effects of each alloy component, and their inter action in the alloy were studied. It has been shown that variations in the basal plane parameter (a) can be used as an indication for the plateau pres sure changes resulting from substitution, giving better fits than variation s in the unit cell volume. Structural anisotropy is discussed as a possible tool for the prediction of the decrepitation resistance of the alloy. Meth ods for optimization of the electrode alloys (including reduction of the co balt content) are proposed. (C) 2000 Elsevier Science S.A. All rights reser ved.