Effect Of Processes On Microstructure And Properties Of Mg-Sn-Zn Alloy

With the advantages including low density, high specific strength, specific rigidity,damping process ability，recyclability and so on, many studies are focused on magnesiumalloys. With high temperature creep resistance and low price, The Mg-Sn-Zn alloy applicationand development are hindered for its poor mechanical properties. In this paper,metallographic, XRD and SEM/EDS techniques and mechanical property testing methodswere used. The effect of contents of Sn and Zn on microstructure and mechanical propertiesof Mg-Sn-Zn alloy of as-cast, T4, T6, hot rolled states were studied. The effect of differentheat treatment and hot rolling processes on the microstructure and mechanical properties ofMg-（5⁶） wt.%Sn-（0²） wt.%Zn alloy were also studied.The results showed:Microstructure structure of Mg-Sn-Zn alloy in casting statue was the dendrite whichcomposited of α-Mg, Mg₂Sn and divorced eutectic. With Zn and Sn content increasing,dendrite arm spacing decreased and mechanical properties improved. When the content of Snexcesses5%, microstructure changes and mechanical properties decreases.In T4treatment, with solution temperature rising and solution time prolonging, dendriteand Mg₂Sn phase gradually disappeared and the twins appeared. Zn can not only decrease themelting point of the alloy, but also inhibit twins generating in T4treatment. In T6treatment,Mg₂Sn phase was precipitated again. With aging temperature rising and time prolonging,Mg₂Sn phase appearing more and more dispersion and mechanical properties of the alloyimproved. When aging time longer than a certain time, mechanical properties decreased foroveraging phenomenon. After T6treatment, twins still existed, The Mg₂Sn numbers werepromoted and the twins number were suppressed with addition of Zn.Dynamic recrystallization was taken place during hot rolling. There were a lot of twinsand a few of substructures in microstructure. With deformation and hot rolling temperatureincreasing, dynamic recrystallization was more and more complete. Addition of Sn and Znpromoted dynamic recrystallization, while improved the mechanical properties of the alloys.During the three state alloys, alloy after rolling had the highest tensile strength, but elongationrate was lower than the other. Alloy after T6treatment had good comprehensive mechanicalproperty.