| China is one of the countries with the most abundant magnesium resources and mineral reserves in the world,and is currently the world's largest producer and exporter of magnesium resources.In addition,magnesium's low density,high specific strength,high electromagnetic shielding and other excellent characteristics are in today's industrial development.The advantages gradually emerged,which led to China's strategy of changing resource advantages into industrial advantages and economic advantages.Magnesium alloy has broad development prospects.Compared with other series of magnesium alloys,Mg-Al alloys have more excellent mechanical properties and corrosion resistance.In this paper,AZ80 is used as the basic alloy,using metallographic observation,scanning electron microscopy,energy spectrum detection,X-ray diffractometer,Vickers hardness tester and electronic universal tensile testing machine and other test methods have conducted an experimental investigation on the influence of different Ca element content on the microstructure,mechanical properties and corrosion properties of the alloy after hot extrusion and heat treatment The following results are obtained:After extrusion deformation,the alloy undergoes dynamic recrystallization to varying degrees,and the crushed second phase is distributed in a band shape along the extrusion direction.The matrix alloy?Mg-8Al-0.5Zn?consists of the?-Mg matrix and the Mg17Al12phase The composition,with the addition of the alkaline earth element Ca content,the hardened phase Al2Ca phase appears in the alloy structure.The average grain sizes of the four alloys are 23.2?m,13.4?m,7.3?m,and 9.7?m,respectively.It can be seen that the addition of Ca element can make the average grain size of the alloy significantly smaller.The optimal content of Ca added to the test alloy is:x=1wt%,which has the best performance at this time,the tensile strength and yield strength at this time are268Mpa,148Mpa,and the elongation is 12.9%.The addition of different Ca elements can also change the self-corrosion potential and self-corrosion current density of AZ80 alloy.Among them,when the Ca content is 1%,the self-corrosion current density of the alloy is the smallest,with a value of 1.87×10-5A/cm2.Then,through the simulated phase diagram during the solidification of the second phase,the structure and properties of the AZ80-x Ca deformed magnesium alloy were investigated by the change of solution conditions,and the solid state of the?-Mg17Al12phase at 430?/10h was obtained.Under the dissolution treatment process,it can be basically dissolved into the matrix.In this process,the alloy is T6 treated.The hot extruded alloy containing 1%Ca has better microstructure distribution and mechanical properties after T6?430?×10h+200?×84h?treatment.The main phase composition is still composed of?-Mg matrix,non-uniformly distributed Mg17Al12phase and Al2Ca phase,its Vickers hardness HV76.4,ultimate tensile strength and yield strength are 289MPa,158MPa,and elongation 22.4%.At the same time,the heat treatment also changes the self-corrosion potential and self-corrosion current density of the alloy.The solution treatment reduces the self-corrosion current density of the AZ80-1Ca alloy,which improves the corrosion resistance of the alloy.Increased self-corrosion current density and reduced corrosion resistance of the alloy. |
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