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.