Effect of Compressive Stress on Reaction-Diffusion in the Cu–Si System

Abstract

Cu–Si diffusion couples were annealed at temperatures from 411 to 461°C under various compressive stresses less than 120 kg/cm2. Regardless of the magnitude of the stress the Cu3Si phase appeared as an only one intermetallic phase in a diffusion zone. Marker experiments showed that copper was the diffusing element. Under the stresses above 80 kg/cm2 the growth of the Cu3Si followed a parabolic law at intrinsic rate at a given temperature. Under the stresses less than 80 kg/cm2 the growth rate of the phase in an early stage of anneal was lower than the intrinsic rate. In the subsequent anneal stage, however, the growth rate tended to be accelerated and approach the intrinsic one. Such growth behaviour of the Cu3Si phase appeared to be explained in terms of the quantitative variation of Kirkendall voids which restricted the transfer of atoms from the copper into the diffusion zone.