Effects of heat treatment system and Cu content on the microstructure and mechanical properties of two conventionally cast Al-Cu-Mn alloys were investigated.It is found that after treatment at proper temperatures,including 525℃×16 h+170℃×8 h for Cu2.8 alloy,525℃×16 h+170℃×14 h for Cu5.7 alloy,the Cu2.8 alloy and Cu5.7 alloy have their tensile strength up to 209.76 MPa and 349.15 MPa respectively,and yield strength reaching 107.15 MPa and 216.21 MPa correspondingly.The detailed exploration of precipitation behavior of the alloy after aging indicates that Cu content brings an important influence to the precipitation behavior.The precipitation of the T phase leads to depletion of Cu atoms in low-Cu alloy during solid solution process.The θ′phases only adhere near the T phase,and dispersed θ″phases are only precipitated in the high-Cu alloy,which contribute mainly to higher strength of high-Cu alloy.
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