Study On Microstructure And Mechanical Properties Of Mg-Al-Ga Magnesium Alloy

Magnesium alloy is one of the lightest practical engineering material,which shows very high specific strength and stiffness,good cast-ability and absorption ability of vibration.However,its strength and plasticity is low.Furthermore,this has limited the application of magnesium alloy,therefore,the research and the development of high performance magnesium alloy has the broad space.The Mg-8%Al-(0-4)%Ga and Mg-(8-12)%Al-2%Ga alloy were investigated in this paper.Metallographic analysis and mechanical property test were used to determine the microstructure and the mechanical behavior of as-cast,heat treatment and extrusion process alloys.The influences of Ga on the microstructure and mechanical properties of Mg-Al-Ga alloy with different contents of Ga,and the influences of heat treatment and extrusion process on the microstructure and mechanical properties of Mg-8%Al-2%Ga were investigated.The results show that the microstructure of magnesium alloy with Ga addition can be significantly improved,and the morphology ofβphase changed from discontinuous network with cavities into bulk with smooth surface,eutectie alongβphase emerged;The EDX analyzing results show that the Ga element mainly exists withinβphase and the junction ofβphase andαphase;The XRD analyzing results show that,the Ga₂Mg phase formed in the alloy when the content of Ga reached to 4%.The Mechanical property test results show that with the adding of Ga the mechanical properties can be significant improved;The hardness of Mg-8%Al-2%Ga and Mg-8%Al alloy after different solution and aging process were investigated;the tensile strength of Mg-8%Al-2%Ga is 248.4MPa, and the elongation ratio is 10.4%after the best heat treatment process;The hardness of Mg-8%Al-2%Ga after extrusion process can be significantly improved;The microstructure results show that a large number of compound twins formed in the Mg-8%Al-2%Ga alloy after extrusion process,and the plates phase are formed in the grain boundary and the compound twins,and the number and size of precipitates increased as the time of aging treatment increasing.Fracture surface analysis revealed that,the Fracture surface of Mg-Al-Ga alloy is cleavage and quasi-cleavage,and a little dimple rose on the surface.The number of dimples increased with Ga addition at the same content of Al.This revealed that the toughness can be improved with Ga addition.The fracture surface of Mg-Al-Ga alloy was cleavage and quasi-cleavage after solution and solution + aging treatment.