时效时间对锻态AZ80镁合金第二相析出及柱面取向表面腐蚀性能的影响

Effect of Aging Time on Precipitation of Second Phase and Corrosion Performance of Prismatic Plane of As-forged AZ80 Mg-alloy

本文对锻态AZ80镁合金进行固溶处理及不同保温时间的时效处理,采用析氢法、失重法及电化学测试分析了时效态AZ80镁合金的耐蚀性能,观察了合金的显微组织和腐蚀形貌,对比研究了时效热处理工艺对于柱面织构平面内第二相形貌、尺寸及数量等特征的影响,探讨了不同特征第二相粒子对合金耐蚀性能的影响规律。结果表明:不同的时效时间可有效调控锻态AZ80镁合金中第二相的析出行为,时效处理不仅可以改善合金的耐蚀性能,还可以有效弱化镁合金腐蚀性能上的各向异性。当合金达到峰值时效时,基体内可形成致密的具有网络结构的第二相,合金表面的耐蚀性和腐蚀均匀性均得到有效提升,柱面取向表面和基面取向表面间平均腐蚀速率的差值最小。

The corrosion resistance of the as-forged AZ80 Mg-alloy subjected to solid solution treatment,and aging treatment for different time was investigated by means of hydrogen evolution method,mass loss method and electrochemical tests etc.Meanwhile,the microstructure and phase composition of the alloy,as well as the morphology and composition of corrosion products were also characterized by OM,SEM and XRD,especially in terms of the effect of microstructure variation and second phase precipitates on the corrosion behavior of the as-aged AZ80 Mg-alloy.The results indicate that varying aging time can effectively adjust the precipitation behavior of the second phase in the forged AZ80 Mg-alloy.Aging treatment can improve not only the corrosion resistance,but also mitigates the anisotropy in the corrosion performance of the Mg-alloy.For the specimen after the peak-aging treatment,a dense second phase with a network structure can be formed in its matrix,which results in the effective improvement of the corrosion resistance and uniformity of the specimen surface.Meanwhile,the difference in average corrosion rate between the cylindrical oriented surface and the basal oriented surface is minimized.