Effect of Cu and Sr on the Microstructure and Mechanical Properties of Al-Mg-Si Based Alloy Sheets

The effects of Cu and Sr elements on the mechanical properties of Al-Mg-Si based alloy sheets were studied by using metallograph,DSC,XRD,SEM and TEM.The quaternary phase-Q phase could form when Cu was added into the alloy.The mechanical properties of aluminum alloy sheets could evidently increase.The tensile strength of aluminum alloy sheet achieved 333MPa and the yield achieved 182MPa when Cu content was 0.84%(wt%).Sr could refine grains of the alloys,promote precipitation and change β(Al5FeSi) phase into α(Al8Fe2Si) phase,and thus increase the mechanical properties of aluminum alloy sheets.Compared to the alloy without Sr,the tensile strength increased 10-20MPa when 0.033%Sr was added into the alloy.