The transport and absorption of H were studied in the as-quenched amorphous state, or after annealing for 1h at temperatures of up to 873K. The diffusivity, and the fractions of mobile and trapped H, were deduced from electrochemical permeation measurements that were carried out at 298K. After annealing below the crystallization temperature of about 560K, the H diffusivity and absorption increased 2-fold whereas, at higher temperatures, they markedly decreased (with the formation of Ni and Ni3P phases) by some 3 orders of magnitude; from 1.5 x 10-13m2/s at 523K to 1.7 x 10-16m2/s at 873K. When tested below the crystallization temperature, the ratio of trapped H to total absorbed H hardly changed with annealing temperature, and was equal to about 0.75. The increase in H diffusivity and absorption below the crystallization temperature was suggested to result from local ordering of the atoms. It was concluded that the behavior of H was a sensitive function of the structural relaxation in the amorphous alloy.

T.Zakroczymski, J.Flis: Corrosion, 1989, 45[11], 908-14