Kinetics of Hydrogen Absorption and Release in Zirconium Alloys During Steam Oxidation

The kinetics of hydrogen absorption during steam oxidation in Zr–Sn and Zr–Nb alloys in the temperature range of 1,000–1,400 °C was investigated by neutron radiography. Hydrogen uptake can be subdivided into two steps: an initial phase and a state of equilibrium. The initial phase is controlled by the kinetics of hydrogen diffusion through the growing oxide layer. In the state of equilibrium, transport kinetics does not determine the hydrogen content of the material. An equilibrium is established between the hydrogen content of the gas environment and the metal phases. The temperature dependence of hydrogen absorption is Arrhenius-like at temperatures between 1,100 and 1,300 °C.