Overheat of Al–Li–Cu–Mg–Zr alloy

Abstract

The overheat of an Al–Li–Cu–Mg–Zr alloy has been investigated using differential scanning calorimetry, optical, transmission electron, and scanning electron microscopy, and electron probe microanalysis. It has been found that this alloy overheats at 547°C. Its features are curved grain boundaries and triangular grain boundaries, which are similar to those of conventional aluminium alloys, but there are no remelted eutectic spheres within the grains. With the occurrence of overheat, the ultimate tensile strength and elongation decrease markedly. This is caused by remelting of the α (Al)+R (Al₅CuLi₃) binary eutectic on the dendritic network. This is a non-equilibrium phase formed during the casting and homogenising processes.

MST/1434