Interdependence of stress and interdiffusion during solid-state amorphization in Ni–Hf

Abstract

The evolution of stress in a Ni–Hf diffusion couple during solid-state amorphization reaction has been monitored by substrate curvature measurements and x-ray diffraction. The latter technique allowed an independent determination of the contribution of changes in stress-free lattice parameter to the stress in the crystalline layers. The results indicate that the amorphous phase forms under a large tensile stress, which relaxes as the reaction progresses. This stress in the amorphous phase is consistent with the volume change associated with the reaction. Stresses in the crystalline, elemental phases are considerably smaller and not affected by the reaction. Low-temperature Ni ion irradiation increases the tensile stress in the diffusion couple. The large observed stress variations are not accompanied by variations in the effective interdiffusion coefficient.