Effect Of Y Content On Microstructure,texture And Mechanical Anisotropy Of Mg-Y Alloy

Rare earth elements Y is an important alloying element in magnesium alloys.Mg-Y alloys and Multi-alloy based on Mg-Y alloys are widely used in aerospace and vehicle manufacturing,and have wide application prospects and development value.In this paper,as cast and wrought Mg-Y alloys with different Y contents were prepared,the effects of Y content on the microstructure and mechanical properties of as cast Mg-Y alloy were studied,and the effect of Y content on the texture and the mechanical anisotropy of wrought Mg-Y alloy was investigated.The research results show that:Y can significantly refine the grain of the cast Mg-Y alloy.With the increase of Y content,the amount of second phase Mg₂₄Y₅ increases in the as-cast microstructure.Due to non-equilibrium solidification,（α-Mg）+Mg₂₄Y₅ is produced in the Mg-3Y alloy.Through the interaction of solid solution strengthening,fine grain strengthening and second phase strengthening,Y improved the hardness and strength of the cast Mg-Y alloy,especially the high temperature strength.In plane compression,the Mg-Y alloy has typical basal texture characteristics,howerever,the texture of{0002}basal plane inclines towards TD1 direction and splits with the increase of Y content.Meanwhile,the strength of the basal texture decreases from 9.1 of Mg to 3.3 of Mg-3Y,and shows the weakened texture obviously.The mechanism of Y weakening the basal texture is mainly that Y decreases the lattice axial ratio（c/a）of Mg,enhances the lattice symmetry,and thus activates the non basal slip,weakening the basal texture.When compressed along the radial（TD）and axial（ED）direction of the wrought Mg-Y alloy,it has obvious mechanical anisotropy.However,the mechanical anisotropy decreases with the increase of Y content.At room temperature（20℃）,when the Y content increases from 0 to 3wt%,the strength difference between TD and ED decreases from 82MPa to 34MPa.At the temperature of 300℃,the stress-strain curve of Mg-3Y alloy compressed along TD and ED is almost coincident,the mechanical anisotropy tends to disappear.