SOLUBILITY OF HYDROGEN IN ZR1-XHOXCO2 (0 LESS-THAN-OR-EQUAL-TO X LESS-THAN-OR-EQUAL-TO 1) ALLOYS

Hydrogen absorption studies were carried out on the pseudobinary system Zr(1-x)Ho(x)Co2 (x = 0.2, 0.4, 0.6 and 0.8) belonging to the C15-type Laves phases in the temperature range RT less-than-or-equal-to T (degrees-C) less-than-or-equal-to 300 and the pressure range 0.001 less-than-or-equal-to P (bar) less-than-or-equal-to 1. Hydrogen absorption was found to increase with increasing holmium concentration. For the compositions x = 0.6 and 0.8, the pressure-composition isotherms indicated the occurrence of a phase transformation. The relative partial molar enthalpy and entropy of hydrogen solution calculated for all the concentrations were found to be approximately -(7-18) kJ (mol H)-1 and -(10-48)J K-1 (mol H)-1 respectively.