Room temperature diffusion in polycrystalline materials: an experimental study of interdiffusion in AuCu alloys

Abstract

Interdiffusion in the macroscopic volume of an Au28Cu72 alloy at 293 to 435 K is observed by means of the movement of a thin (∼ 1 nm) gold overlayer into the alloy during the time of annealing. The measured activation energy of 0.74±0.07 eV is attributed to the migration of mono and divacancies which predominantly takes place in the grain boundaries. The lateral movement of a ∼ 0.6 nm gold overlayer in a mechanically polished surface gives data on surface diffusion at around 330 K. Diffusion at room temperature in general is discussed. It is found that the diffusion coefficients exceed 10⁻²⁷m²sec⁻¹ and activation energies are in the 40 to 100 kJ mol⁻¹ range for low temperature diffusion in the macroscopic volume of most polycrystalline materials.