Effect of Mg Addition on Microstructure and Mechanical Properties of Al-Cu-Mn-Ag Alloy

A series of Al-Cu-Mn-Ag alloys with different Mg content were prepared by ingot metallurgy and thermomechanical treatment. The effects of Mg addition on the microstructure and mechanical properties of the alloys were investigated using tensile testing, differential scanning calorimetry(DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It has been shown that adding Mg can change the process of aging hardening and the sorts of precipitation phase of Al-Cu-Mn-Ag alloy. Increasing Mg content accelerates the aging hardening process of the alloys and decreases the size of Ω phase. The coherent plate-like Ω phase and a small amount of θ′ phase are the predominant hardening phases in the Al-4.45Cu-0.49Mn-0.58Ag-0.82Mg alloy at peak-aged stage at 185℃.