Hydrogen determinations in a zirconium based alloy with a DSC

In the present work a method to measure hydrogen concentrations in zirconium-based alloys was developed measuring simultaneously both, the temperature of terminal solid solubility, TTSSd, and the hydride dissolution heat, Qδ→α, using a differential scanning calorimeter (DSC). The hydrogen concentration measured with that technique, [H]Q, and the values obtained with a standard hydrogen gas meter, [H]HGM, shows a linear relation: [H]Q = (1.00 ± 0.03)[H]HGM| + (9.2 ± 8.0) with a correlation factor of 0.99 in the entire solubility interval in the αZr phase, from 15 to 650 wt. ppm-H. The mean enthalpy value determined with two different criteria for TTSSd and Qδ→α measurements is ΔHδ→α(Q)=39.3±1.5 kJ/mol H. The present method is specially appropriate for alloys where a partition of the overall hydrogen concentration in two phases exists. It is applicable to all hydride forming metals which ideally follows the van't Hoff law.