Diffusion and Absorption of Hydrogen in Liquid-Quenched and Annealed Ni81P91Alloy

Abstract

Abstract Transport and absorption of hydrogen were studied in the Ni81P19 alloy in the as-quenched amorphous state and after annealing for 1 h at temperatures up to 873°K. The diffusivity and the amount of diffusible and trapped hydrogen were determined from electrochemical permeation measurements performed at 298°K. After annealing below the crystallization temperature (Tc ≃ 560°K), the hydrogen diffusivity and absorption rose by up to about twice, whereas at higher temperatures (formation of the Ni and Ni3P phases) they drastically decreased, with a drop in diffusivity being almost three orders of magnitude. Below Tc, the ratio of trapped hydrogen to total absorbed hydrogen almost did not change with the annealing temperature, being about 0.75. The rise in the hydrogen diffusivity and absorption below Tc may result from local ordering of atoms; it demonstrates that the behavior of hydrogen may be a sensitive measure of structural relaxation in the amorphous alloy.