Pressure-composition-temperature hysteresis in C14 Laves phase alloys Part 2. Applications in NiMH batteries

This part of our series of papers reports our efforts to predict sealed cell cycle life from lattice constant a/c ratio and/or PCT hysteresis based on correlations established from our previous studies reported in Part 1. In the case of Ti(21)Zr(12.5)V(14)Ni(21.5-x)Cr(10)Mn(21)Sn(x) alloys, as x is increased the a/c ratio increases and the PCT hysteresis decreases resulting in extended cycle life for the battery. This is in agreement with the results from Part 1. In the case of Ti(18)Zr(15.5)V(14)Ni(24.2-x)Cr(10)Mn(18-y)Sn(0.3)Co(x)Al(y) alloys, the a/c ratio trend was not observed due to existence of more than one C14 phase, but the correlation between PCT hysteresis and cycle life was maintained. in the case of Ti(21)Zr(12.5)V(10)Ni(40.2)Cr(8.5-x)Mn(5.6-y)Co(1.5+x+y)Al(0.4)Sn(0.3) alloys, the cycle life was dominated by the corrosive nature of the alloy affected by the Cr content. As a consequence, predictions from a/c ratio and PCT hysteresis can only be applied to the degree of pulverization in gas phase cycling and not to the sealed cell cycle life. (C) 2009 Elsevier B.V. All rights reserved.