Study Of The Isothermal Sections Of The Mg-Zn-Nd At553K And Mg-Y-Gd At723K

Abstract:Magnesium-based alloys have been widely used as lightweight structural materials in many fields and have been intensively researched. There are still many fundamentally and important questions to be answered before this class of engineering alloys can find much wider applications. For example, the poor plasticity at room temperature and the poor creep resistance at elevated temperature. In order to better understand the effects of rare earth elements and provide guide for alloy design, diffusion triple technique is applied to study on the related system.(1) An isothermal section of the Mg-Zn-Nd ternary system at553K is established. Three ternary phase T1,T3and T4formed in this system. The composition of T1is (27.5-33.9)at.%Mg,(6.7-9.1)at.%Nd and (59.3-63.3)at.%Zn; the composition of T3is (25.4-34.9)at.%Mg,(23.3-24.9)at.%Nd and (41-50.8)at.%Zn; the composition of T4is (18.8-21.9)at.%Mg,(12.7-14.6)at.%Nd(at.) and (64.6-67.8)at.%Zn. Ten tri-phase equilibrium:Mg3Nd+T3+α(Mg), T1+Mg12Zni3+α(Mg)， T1+Mg12Zn13+Mg2Zn3, T1+M王Zn3+MgZn2,T1+MgZn2+NdZn3, T1+T4+NdZn3, T3+T4+NdZn3, T3+NdZn2+NdZn3, Nd+Mg3Nd+NdZn2and T3+Mg3Nd+NdZn2, have been identified in the isothermal section.(2) An isothermal section of the Mg-Y-Gd ternary system at723K is established. All the binary phase can be detected in the diffusion triple. Seven tri-phase equilibrium:Mg3Gd+Mg2Y+Mg5Gd, MgGd+Mg2Gd+MgY, MgGd+MgY+Y, Mg5Gd+Mg2Y+Mg24Y5, Mg24Y5+Mg+Mg5Gd, Mg2Gd+MgY+Mg2Y and Mg3Gd+Mg2Gd+Mg2Y, have been identified in the isothermal section.