Compound formation and kinetics in Al–Pd2Si reactions

Abstract

Lateral diffusion couples containing Al islands on Pd–Si multiple layers are used to study Al–Pd2Si reactions. The Pd2Si phase was first formed in the Pd–Si multiple-layer region after furnace annealing at 225 °C. Then, the Al–Pd2Si lateral couples were in situ annealed in a transmission electron microscope at temperatures ranging from 377–438 °C. The laterally growing region is composed of the Al3Pd2 compound and Si precipitates, as identified by selected area diffraction (SAD). During the in situ anneals, transmission electron microscopy (TEM) images were recorded by a video cassette recorder allowing thereafter a kinetic study. The lateral growth is parabolically dependent on the annealing time. An activation energy of 1.7 eV is found for this diffusion process.