Heat content of zirconium and of 5 compositions of zirconium hydride from 0-degrees-c to 900-degrees-c

Abstract

Using a precise Bunsen ice calorimeter, a''silver core'' furnace, and a''drop'' method, the heat content (enthalpy) of zirconium metal and five samples of zirconium hydride (24 to 52 atomic percent hydrogen) was measured over the range 0°C to 900°C. Thermal hysteresis of the hydrides was investigated in several cases, and corrections were applied for the impurities in the samples. At each temperature up to 550 deg C the heat contents of the hydrides relative to 0°C were found to vary linearly with composition, a fact in accord with the phase diagram of the system. The effective heat capacity of each hydride sample reached its maximum value between 550° and 500°C, a behavior that can be interpreted as due to the endothermic formation of the high-temperature beta phase.