稳定化对船用Al-6.0Mg-0.11Zr合金晶间腐蚀的影响

Effect of stabilization on intergranular corrosion of marine Al-6.0Mg-0.11Zr alloy

采用光学显微镜(OM)、电子显微镜(SEM)、透射电镜(TEM)等分析测试手段研究稳定化处理对新型中高强可焊合金(Al-6.0Mg-0.11Zr)晶间腐蚀行为的影响和β相的析出特性,确定该合金稳定化处理的温度与保温时间区间。研究结果表明:Al-6.0Mg-0.11Zr合金中的β相极易沿晶界析出,导致该合金耐蚀性能大幅度降低。稳定化处理可促使沿晶界连续析出的β相产生回溶,并形成亚结构。这种在界面或内部形成细小的、点状的、弥散的β相可以提高合金的耐蚀性能。Al-6.0Mg-0.11Zr合金最佳的稳定化处理温度为240~250℃,最短的保温时间为10 h,延长保温时间有利于晶界β相的回溶,致使后续过程析出更高数密度的点状且弥散的β相。

The effect of stabilization treatment on intercrystalline corrosion behavior andβphase precipitation of a new medium-high strength weldable alloy(Al-6.0mg-0.11Zr)was investigated by means of optical microscopy(OM),electron microscopy(SEM)and transmission electron microscopy(TEM).The temperature and holding time interval of the stabilization treatment were deter⁃mined.The results show thatβphase precipitates easily along grain boundaries in Al-6.0Mg-0.11Zr alloy,which results in a signifi⁃cant decrease in corrosion resistance of the alloy.Theβphase precipitated continuously along the grain boundary can be redissolved and substructure can be formed,which can form small,point and dispersedβphase at the interface or in the interior,and improve the corrosion resistance of the alloy.The optimal stabilization temperature of Al 6.0Mg-0.11Zr alloy is 240~250℃,and the shortest holding time is 10 h.The prolonged holding time is favorable for the redissolution ofβphase at grain boundary,resulting in the pre⁃cipitation of higher number density point and dispersionβphase in the subsequent process.