Kinetics of hydrogen absorption/desorption in TC21 alloy

The kinetics of hydrogen absorption/desorption in TC21 alloy have been investigated under different initial hydrogen pressure at the temperature range of 575-850 °C. At lower temperature and initial hydrogen pressure, the incubation period was longer and the hydrogen pressure needed longer time to reach equilibrium. With the increase of temperature and initial hydrogen pressure, the incubation period decreased and even disappeared. At the second hydrogen absorption stage, the hydrogen absorption process obeyed 3-dimension diffusion process and the mechanism function was kt = [1 - (1 - α)^1/3]². The rate constant of hydrogen absorption increased with increasing temperature at the same stage. The activation energy of hydrogen absorption was found to be 38.43 kJ/mol.