Effects Of Rare Earth Element On The Microstruture And Properties Of Mg-5Zn-2Al Magnesium Alloy

Magnesium and Magnesium alloys are called "The important green-engineering structural material of 21th century "with its high specific strength,specific stiffness and hardness,good electromagnetic shielding characteristics and good machinability,recyalability and abundance,Magnesium alloys have great potential application value and prospect in automobile industry,space,aircraft,electronic,communication and defence industry fields as light-weight structural material.The Mg-5Zn-2Al magnisium alloy is the main subject investigated in this paper,and studied the influnce of Zr and Nd on microstructure and mechanical properties of change regularity.The results indicate that besides the microstrcture is refined,the mechanical properties are also improved obviously when different contents of Zr are added into the Mg-5Zn-2Al magnisium alloy,while the tensile strength and elogation arise first and descend later on either as-east or heat-treatment condition,at the same time the comprehensive mechanical properties reach the best when the content of Zr is 0.6%,moreover the tensile strength of Mg-5Zn-2Al-xNd alloys is increased clearly after T6 heat-treatment.When different contents of Nd and Y added into the Mg-5Zn-2Al alloy, the grain is refined,the microstructure bacome more disperse,meanwhile the mechanical properties are marked improved.The mechanical properties(including tensile strength and elogation) of Mg-5Zn-2Al-xNd reach the most value with 0.6%content of Nd added,the tensile strength and elogation is 204MPa and 11.13%respectively,with the content of Nd further increasing,the mechanical properties begin to descend.When the addition of Y is 0.3%,the Mg-5Zn-2Al-xY alloys have the best comprehensive meshanical properties,correspondingly the tensile strength and elogation is 205MPa and 12.63%respectively.After different contents and proportions of Zr and Nd added into the Mg-5Zn-2Al alloy,the microstructure of the alloys are refined to some degree and over-all mechanical properties are increased.With increasing content of Nd,the mechanical properties take on the same vary trend that arising first and descending later to the alloys which added the same content of Zr,on whatever condition of as-cast or heat-treatment.When the addition of Nd is 0.6%,the Mg-5Zn-2Al-xZr-0.6%Nd alloys have the better performance index,among them Mg-5Zn-2Al-0.3%Zr-0.6%Nd alloy reach the maximum,tensile strength and elogation is 210MPa and 13.75% respectively.