Microstructure and plasticity of an AI–AI 6 Fe directionally solidified eutectic alloy

Abstract

The microstructure and plasticity of a directionally solidified Al-Al₆Fe eutectic alloy was investigated using quantitative STEM-EDX microanalysis, in situ tensile testing in STEM/SEM, and light/electron optical studies of microstructure before and following drawing and extrusion to wire. It is found that in spite of the brittle nature of the aligned Al₆Fe rods, the alloy as a whole is relatively ductile and can even be drawn or extruded to wire. In the deformed condition the Al₆Fe rods are broken up and the fragments distributed uniformly throughout the aluminium matrix. The tensile strength and ductility of these drawn wires are good, 400 MN m⁻² and 83% area reduction, respectively. Microanalysis studies show that the iron content of the aluminium matrix following solidification is 0·04 at.-%, corresponding to an undercooling of ∼3 K below the eutectic temperature. The iron content of the matrix can be reduced further by precipitation treatments.

MST/86