Microstructure And Properties Research Of Mg-Zn-Ca Alloy Under The Action Of Magnetic Field

Magnesium and magnesium alloys have attracted increasing attention as thelightest metal structure material of industrial application due to their lowdensity，high strength，specific stiffness and has a good biocompatibility withhuman body．Especially in recent years with the development of the automotive,electronics and aerospace and other fields, the development of magnesium alloyshas put forward higher requirements． So it is necessary to develop newmagnesium alloy materials and explore its new preparation methods．In this paper, Mg-xZn-Ca alloy was prepared under the effect ofelectromagnetic stirring, then these alloys were homogenizing heat treated, andstudy the effect of electromagnetic field on the microstructure and mechanicalproperties of Mg-xZn-Ca alloy on this basis. Then hot extrusion of magnesiumalloys was conducted under different hot extrusion process to improveorganization and mechanical properties of the alloy.The effect of zinc content, electromagnetic stirring, heat treatment andextrusion process on microstructure and properties of Mg-Zn-Ca alloy werestudied in order to get the best mechanical properties of Mg-Zn-Ca alloy.Microstructure, phase composition, fracture morphology and mechanicalproperties testing of the prepared alloys were analyzed by means of opticalmicroscope, scanning electron microscope, XRD diffraction (XRD), HDV-1000microhardness tester and CSS electronic universal testing machine to obtainperformance parameters of designed alloys in different process and condition.The microstructure and mechanical properties of Mg-Zn-Ca alloy whichprepared under the effect of electromagnetic stirring were analyzed in order todetermine the content of Zn element in which the Mg-xZn-Ca alloy have the bestperformance. Found that under the effect of electromagnetic stirring the element of Zn in addition to have the effect of refining grain, also produced the effect ofstrong solid solution strengthening．The Mg-xZn-Ca alloy achieved the bestmechanical properties when the content of Zn is4.0wt.%. The yield strength,tensile strength and elongation reached101MPa,209MPa and13%,respectively, microhardness value is50.42HV.The microstructure and mechanical properties of the as-cast and heattreatment Mg-Zn-Ca alloys without and with electromagnetic stirring werestudied, and the results show that alloy grain refinement by electromagneticstirring， grain boundary precipitates reduce and second phase distributionuniform，the mechanical properties was improved. Especially grains becomeuniform roundness after homogenizing annealing, precipitation of second phasetransformation of small and scattered, mechanical properties furtherimprovement of the alloy.The hot extrusion of magnesium alloys was conducted by changing differentextrusion die of different extrusion ratio rod extrusion dies and the effect ofdifferent extrusion process on the microstructure and mechanical properties wasresearched. The results shows that the dynamic recrystallization were happenedduring the hot extrusion, grains of the alloy get Obvious refinement, Themicrostructure is composed of uniform fine isometric. The mechanical propertiesalso had obvious enhancement after extruding. When the temperature isT=330℃, extrusion ratioλ=25, the alloy get the highest mechanics performance,The yield strength, tensile strength and elongation reached244MPa,307MPaand19.5%, respectively, the microhardness reached75.26HV.