Phase Transformations of 1.4 at % Cu–Al Binary Alloy at High Pressures and Temperatures

Abstract

Phase transformations of 1.4 at % Cu + 98.6 at % Al alloy have been studied at atmospheric pressure by differential scanning calorimetry and at a moderately high hydrostatic pressure (~100 MPa) by differential barothermal analysis. High pressure has been shown to raise the solvus (θ-Al₂Cu + α-Al → α-(Al) solid-state transformation) temperature of the alloy relative to the equilibrium value obtained at atmospheric pressure. According to our estimate, the heat of solid-state θ-phase dissolution in the α-matrix at 100 MPa is four times that at atmospheric pressure. High-pressure crystallization has been shown to have a significant effect on the microstructure of the alloy, with a manyfold increase in the particle size of the θ-Al₂Cu intermetallic phase.