Kinetics of hydrogen absorption by yttrium dihydride powder

The kinetics of hydrogen absorption by a powder of yttrium dihydride is investigated. A sample having a known specific surface area and a composition close to the lower concentration boundary of the homogeneity region of dihydride is saturated with hydrogen in a Siverts apparatus at 300–450°C and hydrogen pressures of 5–45 kPa. The diffusivities of hydrogen ( D H ) are evaluated on the basis of absorption kinetic curves using a previously developed technique based on the possibility of ignoring the surface curvature at degrees of saturation tending to zero. The temperature dependence of D H (m 2 /s) in the range of 300–450°C is log D H = −12.7 − 1770/T.