Al-11Si-2.5Cu-Mg aluminum alloy was prepared by metal casting method.Effects of heat treatment on microstructure and properties of the alloy were investigated by means of metallurgical microscope and tensile testing.The results show that the properties of Al-11Si-2.5Cu-Mg aluminum alloy can be further improved by heat treatment.The optimized heat treatment process for the alloy is presented as follows:510 ℃×7hsolid solution+160 ℃×8haging treatment

where tensile strength and elongation of the Al-11Si-2.5Cu-Mg aluminum alloy reach 385 MPa and 8.2%

respectively.After heat treatment

eutectic silicon phase in as-cast microstructure is transformed into spherical ones

and most of fine and dispersedly Al

2

Cu and Mg

2

Si strengthening phases are precipitated fromαsolid phase

improving strength of the alloy.