Influence of the Composition on the Solidification Path, Microstructure Evolution and Mechanical Properties of Al-Cu-Mg Alloys

Abstract

The influence of the initial composition on the solidification path, microstructure evolution, thermophysical properties and mechanical properties of Al-Cu-Mg alloys was investigated. The solidification paths of the investigated alloys were determined by analyzing the solidification structure, and then the experimentally determined paths were compared with those from the calculated results. Three of the investigated alloys experienced typical ternary eutectic solidification, and the other four alloys experienced quasiperitectic reactions. Due to differences in the initial compositions, different eutectic morphologies were formed during the solidification process. The binary eutectic phases, (α-Al + Al2Cu) and (α-Al + Al6CuMg4), and the (α-Al + Al6CuMg4 + Al8Mg5) ternary eutectic phase tended to exhibit divorced growth, and the (α-Al + Al2CuMg), (α-Al + Al6CuMg4) and (α-Al + Al2Cu + Al2CuMg) eutectic phases tended to exhibit coupled growth. The results indicated that the initial composition, solidification path, microstructure and morphology could greatly affect the melting enthalpy, microhardness and compressive strength of the investigated Al-Cu-Mg alloys.