Abstract: Phosphorus segregation and embrittlement of Ni-P amorphous annealed at the temperatures below crystallization have been investigated.The phosphorus enrichs on free surface and its level increases with annealing temperature.This is fairly coincident with the measured toughness which decreases with annealing temperature.AES ion-sputtering revealed that a phosphorus depletion zone in the subsurface layers forms due to element redistribution during annealing.The thickness and amplitude of the phosphorus depletion zone depend on the an- nealing temperature. The formation of depletion zone and the mechanism of embrittlement of Ni-P amorphous during annealing have been discussed based on the theory of the activation energy of atomic diffusion in the amorphous being variable.

Key words: Ni-P amorphous, phosphorus segregation, annealing embrittlement