Intermetallic growth under high hydrostatic pressures

The kinetics and atomic mechanisms of intermetallic growth during bulk and surface interdiffusion in binary metallic systems have been considered. Two types of diffusion experiments are discussed: 1) bulk interdiffusion between the A and B metals that results to the growing A_mB_n intermetallic layers, and 2) surface diffusion from the A layer with a sharp boundary placed onto the substrate B, so that the intermetallic compound A_mB_n forms and spreads along the surface. The kinetic regularities of the bulk and surface intermetallic growth are analyzed theoretically, and the methods for determination of diffusion characteristics and kinetic coefficients of interfacial chemical reaction are proposed. The developed methods are applied for experimental measurements of the phase growth kinetics for the Cd-Ni, Cd-Cu, and Zn-Cu systems in the temperature range 160-280°C under hydrostatic pressures up to 1 GPa. Application of high pressure allowed evaluating the activation volumes for bulk and surface diffusion, as well as for chemical reaction at interfaces. On the base of these data and measured diffusion activation energies and pre-exponential factors atomic mechanisms for chemical reactions as well as for bulk and surface diffusion in the growing intermetallics are suggested.