Quantitative Characterization of Microstructure and Mechanical Properties of Al-Cu-Mn Alloys Based on Mg and Sc Alloying

It is well known that alloying is one of the effective methods to control the microstructure and improve the comprehensive properties of alloys. In order to develop Al-Cu-Mn alloys with high strength, we studied the microstructure and mechanical properties of Al-Cu-Mn alloy and Al-Cu-Mn-Mg-Sc alloy under T6 heat treatment and quantitatively characterized the effect of Mg and Sc on the properties of Al-Cu-Mn alloys. The results show that the addition of Mg and Sc refines the grain size of the alloy significantly. The yield strength and ultimate tensile strength increase from 222.9 to 278.5 MPa and 280.4 to 346.0 MPa, respectively, and the elongation decreases slightly from 8.68 to 5.98%. The quantitative characterization shows that the precipitation strengthening is the main strengthening mechanism, and the contributions of precipitation strengthening to the yield strength of Al-Cu-Mn alloy and Al-Cu-Mn-Mg-Sc alloy are 96.1 and 141.8 MPa, respectively.