In Situ Particle Al < Sub > 4 < / Sub > C < Sub > 3 < / Sub > On The Microstructure And Mechanical Properties Of As-cast Az91d Magnesium Alloy

Cast magnesium alloy are widely used in various industrial fields becauseof its advantages of low density, flexible manufacturing, high specific strength,but still far below other major metal materials, which is due to its owndeficiencies of low strength, brittleness and mechanicalperformance.Therefore,the study to improve its grain structure by means of grain refinement and then toimprove the microstructure and mechanical properties of the alloy, this hassignificance means for the play potential applications and performanceadvantages of magnesium alloy material.This article studies the cast magnesium alloy AZ91D alloy which is widelyused.By adding MgCO₃and CaCO₃to alloy melt,we obtain Al₄C₃by in-situreaction.Study the effect of Al₄C₃to the microstructure and mechanicalproperties of AZ91D magnesium alloy, and analysis thermodynamics andkinetics conditions of the in-situ reaction. By means of OM, XRD, SEM, EDS,universal tensile testing machine and hardness tester to comparative analysis theeffect of Al₄C₃that generated in-situ to the alloy’s microstructure andmechanical properties after added different levels of MgCO₃and CaCO₃. Theresults showed that:By adding MgCO₃or CaCO₃in AZ91D magnesium alloy melt to produceAl₄C₃particle bythe in-situ reaction, and refine the alloy significantly.The β-Mg17Al12phase morphology transform from chunks of completelydivorced eutectic structure （α） to partially divorced eutectic structure （α+β）.In-situ particles Al₄C₃generated with the addition of1.0ωt%MgCO₃（CaCO₃）effect alloy grain best, the average grain size and the average area drasticallyreduced, generated in-situ particle which makesthe AZ91D alloyobtainefine-grained microstructure on the condition oflower undercooling.Mechanical testing and analysis shows, the Al₄C₃particles generated in-situcan significantly improve the hardness, tensile strength and elongation ofAZ91D magnesium alloy, add1.0ωt%of MgCO₃or CaCO₃willmost effective tostrengthen the mechanical properties of alloys. grain refinement and second phase strengthening are the two main ways to strengthen and toughenalloy,where the former plays a dominant role.Comparative the microstructure and properties of adding MgCO₃andCaCO₃, we can get the conclusion of adding MgCO₃can effetely refineorganization of the alloy and the more excellent mechanical properties under thesame conditions.