均匀化退火对Mg-6Al-5Pb-0.6Ce镁阳极组织和性能的影响

Effect of Homogenization on Microstructure and Properties of Mg-6Al-5Pb-0.6Ce Magnesium Anode

采用熔炼铸造法制备Mg-6Al-5Pb-0.6Ce合金阳极材料,采用X射线衍射(XRD)、环境扫描电镜(ESEM)研究均匀化退火对Mg-6Al-5Pb-0.6Ce合金显微组织的影响;采用恒电流放电、动电位极化扫描研究均匀化退火前后该镁合金的腐蚀电化学性能。结果表明:经400℃均匀化退火24h后,合金中呈岛状分布的β-Mg17Al12相完全固溶于镁基体,成分偏析基本消除;与铸态合金相比,均匀化退火态合金中有效阴极相(β-Mg17Al12相)的消失使合金电偶腐蚀减少,耐蚀性提高;均匀化退火后,合金的平均放电电位从-1.756V(相对SCE,下同)正移到-1.726V,放电活性略微减弱,而阳极利用率提高5.1%,达到79.8%。

Mg-6Al-5Pb-0.6Ce alloy anode was prepared by melting and casting.The effect of homogenization on microstructure of this alloy was investegated by XRD and SEM.Its corrosion and electrochemical behavior before and after homogenization of the alloy were studied by potentiodynamic plorization and galvanostatic discharge.The results indicated that the island-likeβ-Mg17 Al12 phase was dissolved into the magnesium matrix and the composition segregation almost disappeared after homogenizing at 400 ℃ for 24 h.Compared with the as-cast alloy,the disappearance of the effective cathodic phase（β-Mg17Al12）in the homogenized alloy led to a decrease of galvanic corrosion and an improvement of corrosion resistance.Moreover,the discharge potential of Mg-6Al-5Pb-0.6Ce magnesium anode was shifted from-1.756 V（SCE）to-1.726 V（SCE）after homogenization,resulting in a weakening of the discharge activity.However,its anode utilization efficiency reached 79.8%,which was 5.1%higher than that of the as-cast alloy.