Microstructure and Mechanical Properties of Al-5Cu-4.5Mg-2.5Zn Squeeze Cast Alloy

Abstract

Al-5Cu-4.5Mg-2.5Zn alloy was prepared and the alloy ingots were fabricated by squeeze casting in this work. Considering these negative effects of composition segregation and coarse second phases, some heat treatments were adopted in this research. Microstructures, element distribution, phase constitutions and mechanical properties of Al-5Cu-4.5Mg-2.5Zn alloy ingots before and after heat treatments were investigated. It was discovered that these heat treatments would influence and extremely optimize the microstructures and properties of Al-5Cu-4.5Mg-2.5Zn alloy. Except some residual S (Al₂CuMg) phase and a few of η phase, the precipitate free zone (PFZ) and the Guinier Preston zone (GPZ) formed in the alloy. It was also found that θ″ (Al₂Cu) and η″ (MgZn₂) phases formed and kept a consistent relationship with the aluminum matrix. As the result, these properties of ultimate tensile strength (UTS), percentage of elongation and Brinell hardness (HB) were greatly elevated. The UTS, percent of elongation and HB were 469 MPa, 8.1% and 208 N/mm², respectively.

Keywords

Al-Cu-Mg-Zn alloy / squeeze casting, heat treatments / second phases / mechanical properties