The Research About Extrusion Deformation After Aging Strengthening For MgSnMn And MgSnZnMn Alloys

Magnesium and magnesium alloys are known as green materials of 21st century due to its unique mechanical properties, fine biocompatibility and biodegradability, which leads to a great prospect in clinical cardiovascular, oral cavity, orthopedics, surgery and other clinical fields. Magnesium alloys cannot be used widely in clinical field because of its worse mechanical properties.Currently, there are several ways, such as alloying strengthening, heat treat strengthening,deform strengthening to improve the mechanical properties of the magnesium alloys. In this paper, the two medical alloys Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn were prepared by melt casting method. These two alloys were aging treated at four different temperature: 160?,180?, 200? and 240?. The evolutionary feature of microstructure and the micro-hardness at different aging time were studied to optimize the parameters of aging treatment. The 10mm and 20mm diameter test bars of the Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn being aging treated at different parameters and non-treated ones were obtained by extrusion process under different temperature and deformation. With the microstructure and mechanical properties of the test bars been characterized by optical microscopy, SEM and tensile test, the influence of the aging treat on the deformation properties of the two alloys was studied systematically.The results showed that the second phase of the Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn alloys were individually precipitated slowly with fine morphology and dispersion during treating at 160?, and the second phase and the grain size were not significant change after over aging period. Among all the parameters, the properties were the best when age treated at 160?.Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn, which were treated by solid solution and 160? aging, were extruded at the same parameters (extrude temperature: 300?, extrusion ratio: 16), then tested their tensile strength, the results showed: peak-aging treated alloy was better than others. The highest tensile strength of two magnesium alloys were 264.8 MPa and 275.7 MPa, respectively, the grains of alloys showed small dimension and good uniformity.The results above implies that Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn alloys could be aging strengthen and improved the extrusion performance after 160? aging treatment.After being extruded at different parameters (extrude temperature: 300?, 350?;extrusion ratio: 16, 64), the microstructure and mechanical properties of Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn alloys peak-aging treated at 160? were studied. The result showed when the extrusion temperature was 300? and extrusion ratio was 64, the grains and second phase of alloys were small dimension and good uniformity. And the tensile strength was increased to 271.9MPa and 283.3MPa, respectively. So the comprehensive properties of Mg-3Sn-0.5Mn and Mg-3Sn-1Zn-0.5Mn alloys were optimum when the extrusion temperature was 300? and extrusion ratio was 64.