Study On As-cast Mg-Sn-Al Magnesium Alloy

Magnesium alloy is one of the lightest alloys in the structural materials. Ithas been widely applied in the automotive, rail transportation,3C products,aerospace, etc. Meanwhile biological, hydrogen storage, superconductivity andsemiconductor also use magnesium alloys. Mg-Sn-Al alloy is a new kind of lowcost, good mechanical properties, resistance to creep properties and castingproperties. In order to further enhance the mechanical properties of magnesiumalloys, alloying or plastic deformation is widely used at present.The studied Mg-Sn-Al alloys with different composition are prepared bypermanent mold casting.On the basis of TA74alloy, alloying is the selectionalkaline earth elements (Ca, Sr)and rare earth elements (Y, Ce) as alloyingelements, and then select the two kinds of typical alloy (TA74and TAJ743) toconduct extrusion experiment. By OM, XRD and SEM,the studied alloys’microstructures are observed; by using electronic universal testing machine,thestudied alloys’mechanical properties are tested. The results showed that:1) Among Mg-Sn-A1alloys, TA74alloy owns the best comprehensivemechanical properties，which consists α-Mg, Mg2Sn phase and β-Mg17Al12phase. 2) On the basis of TA74alloy, after adding the right amount of alkalineearth elements (Ca, Sr), the alloy grain is refined, significantly improving theorganization of the studied alloys. For TA74-xCa alloys (x=0,1,2,3), thestudied alloy consists α-Mg phase, Mg2Sn phase and CaMgSn ternaryphase,and CaMgSn ternary phase is tiny particles. When the Ca content is2wt.%, the alloy grain is the most tiny, whose average grain size reduced from81μm to54μm and comprehensive mechanics performance is the best; With theCa content increasing, CaMgSn ternary phase will gradually become a roughacicular phase, and its mechanical performance is worse. For TA74-xSr alloys(x=0,2,3,4), the Sr added,the studied alloy consists α-Mg phase, Mg2Sn andSrMgSn ternary phase; when the Sr content is3wt.%,the alloy owns the mostsmall grains and the most comprehensive mechanical performance.3) After adding right amount of alkaline earth elements (Ca, Sr), themechanical properties of TA74alloy can all improve. The hardness of TA74-xCa (x=0,1,2,3) alloys increases gradually; as the Ca content increases, vickershardness value from54.3HV (TA74) is increased to72.4HV (TA74-3Ca).When the Sr content is3wt.%, TA74-3Sr alloy shows the best comprehensivemechanical properties,whose tensile strength, yield strength and elongation is197Mpa,165Mpa and5.6%, respectively.4) On the basis of TAJ743alloy, adding right amount of rare earth elementCe, the alloy grain refined, but the rods generate adverse to the performance ofmechanical property. For TAJ743alloy based alloy,2wt.%Ce, or add1wt.% Y added refine the organization of the studied alloy, and tensile properties areimproved compared with TAJ743based alloy,.5) By comparing TA74and TAJ743alloy before and after extrusion, itsgrain sizes have been refined obviously, and its mechanical properties areimproved significantly.