Diffusion formation of intermediate phases and supersaturated solid solutions in the aluminum−copper system

Abstract

Studies of the processes that occur upon the interdiffusion in the aluminum−copper system in the temperature range of 320–440°C have been carried out using optical metallography, scanning electron microscopy, and electron microprobe analysis. It has been found that, in this system, at low annealing temperatures, there are no intermediate phases that correspond to the equilibrium phase diagram. Short-term high-temperature annealing leads to the formation of the equilibrium phases. The subsequent low-temperature annealing leads to the precipitation of a second phase from the solid solution in the form of particles rather than layers. It has been shown that the absence of the equilibrium phases is accompanied by the formation of a supersaturated solid solution of copper in aluminum.