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 Ti21Zr12.5V14Ni21.5−xCr10Mn21Snx 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 Ti18Zr15.5V14Ni24.2−xCr10Mn18−ySn0.3CoxAly 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 Ti21Zr12.5V10Ni40.2Cr8.5−xMn5.6−yCo1.5+x+yAl0.4Sn0.3 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.