摘要
采用金相显微镜、扫描电镜、透射电镜、静态浸泡及电化学测试手段研究了时效处理对高应变速率轧制Mg-4Zn合金板材微观组织和耐腐蚀性能的影响.结果表明:轧制态Mg-4Zn合金组织由细小均匀的动态再结晶晶粒组成,平均晶粒尺寸为3μm,合金内部析出相分布不均匀,局部区域存在位错;预时效(70℃/10 h)处理后合金内部析出大量GPI区(长度3～10 nm,宽约2～3个原子间距)和球状GPII区(直径4～10 nm);70℃/10 h+160℃/2 h时效处理后合金内部位错密度显著降低且析出相分布更为均匀;Mg-4Zn合金在Hank's溶液中的腐蚀形式为丝状腐蚀与点状腐蚀相结合;随着时效时间的延长,其耐腐蚀性能呈现先升高后降低的趋势.时效2 h时合金的耐蚀性达到最佳(平均腐蚀速率为0.28 mg·cm-2·d-1,腐蚀膜厚约6.3μm,腐蚀电位为-1.41 V,腐蚀电流密度为11.8μA/cm2),可归因于时效后位错密度降低、析出相分布更为细小均匀.
The effect of aging treatment on the microstructure and corrosion resistance of Mg-4Zn alloy sheets prepared by high strain rate rolling was investigated by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscope(TEM),static immersion and electrochemical measurement.The results show that the as-rolled Mg-4Zn alloy is composed of fine homogenous dynamic recrystallization grains with the average grain size of3μm and many non-uniformly distributed precipitates.Dislocations are observed in some local regions.After pre-aging treatment,a large number of GP I zones(up to about3~10nm in length,2~3atomic spacing in width)and ball-like GP II zones(up to about4~10nm in diameter)are formed in the grains.Dislocation density is significantly reduced,and precipitates are more uniformly distributed in the Mg-4Zn alloy aged at70℃/10h+160℃/2h.A combination of filament corrosion and pitting corrosion is the corrosion mode of as-aged Mg-4Zn alloy in Hank's solution.With the prolonged aging time,its corrosion resistance increases at first and then decreases,and the alloy aged at70℃/10h+160℃/2h exhibits the best corrosion resistance due to the reduced dislocation density and the uniform distribution of precipitates.The average corrosion rate,the thickness of corrosion film,corrosion potential and corrosion current density are0.28mg·cm^-2·d^-1,6.3μm,-1.41V and11.8μA/cm2,respectively.
作者
陈吉华
周博
严红革
夏伟军
苏斌
巩晓乐
CHEN Jihua;ZHOU Bo;YAN Hongge;XIA Weijun;SU Bin;GONG Xiaole(College of Materials Science and Engineering,Hunan University,Changsha410082,China;Hunan Provincial Key Laboratory of Spray Deposition Technology and Application,Hunan University,Changsha410082,China)
出处
《湖南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2018年第12期38-45,共8页
Journal of Hunan University:Natural Sciences
基金
国家自然科学基金资助项目(51571089)~~
