The Effect Of Rare Earth Er On AZ31B Magnesium Alloy Of Cast Microstructure And Performance

We used many kinds of analytical methods,including opticalmicroscopy(OM),scanning electron microscopy(SEM), energy spectrumanalysis(EDS),tension test and hardness test, for systematically studing theinfluence of Er addition into AZ31B magnesium alloy to its microstructure, basedon AZ31B magnesium alloy corrosion resistance and mechanical properties.The results indicate that the addition of earth Er can significantly refineAZ31B magnesium alloy grain, change the dendritic morphology of alloy;eutecticβ-Mg17Al12phase changes from irregular reticulation or chain into islandor block, and appears the granular second phase.intracrystalline or at thecrystalline boundary.0.4%Er-AZ31B magnesium alloy has minimum grain anduniform phase distribution. And, Er content increases, following rising trend toreduce the mechanical properties of the alloy.As-cast hardness of alloy reachespeak value when addition of Er takes0.4percent. The result of soakingexperiment shows that corrosion rate of AZ31B magnesium alloy with0.4%Er isonly25.46%of magnesium alloy when soaking in3.5%mass concentrationNaCl solution, which is the minimum rate of the alloy.This paper analyzes and discusses the mechanism of rare earth Er corrosionresistance and mechanical properties of magnesium alloy significantly improve.Er addition can purify alloy liquid, refine matrix grain, homogenize alloycomposition. The improving pattern,quantity and distribution of eutecticβ-Mg17Al12phase can increase granular second phase in matrix. Granular secondphase spreads in the crystal boundary and matrix. Moreover, intrinsic earth Er inmatrix combine with O firstly, forming earth oxide, then contributing forprotection to matrix.