时效处理对含钪Al-Zn-Mg-Zr合金腐蚀行为的影响  

Influence of aging treatment on corrosion behavior of Al-Zn-Mg-Zr alloy with Sc element

作　　者：李波[1] 潘清林[1,2] 李晨[1] 史运嘉 张志野[1] 尹志民[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083 [2]中南大学有色金属材料科学与工程教育部重点实验室,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2013年第10期3998-4005,共8页Journal of Central South University:Science and Technology

基　　金：国家重点基础研究计划(“973”计划)项目(2012CB619503)

摘　　要：采用恒温浸泡法、极化曲线测试、慢应变速率拉伸试验、扫描电镜及透射电镜等分析手段,研究时效处理对含钪Al-Zn-Mg-Zr合金腐蚀行为的影响。实验结果表明:合金在自然时效态下具有较差的抗晶间腐蚀和剥落腐蚀能力;合金腐蚀敏感性随着时效制度的变化由小到大的顺序为:T73时效,T6时效,欠时效,自然时效。经极化曲线测试分析,合金的腐蚀性能呈现相同趋势。在同一慢应变拉伸速率下,T73时效态的应力腐蚀敏感性相比T6时效态低;在相同时效状态下,应变速率为1.33×10 6s 1的应力腐蚀敏感性相比6.67×10 6s 1的高。合金的腐蚀敏感性与时效析出相(MgZn2)尺寸、分布及无沉淀析出带(PFZ)有关,在T6时效态下,晶界析出相连续的链状分布导致腐蚀敏感性大;同时,晶界析出相的粗化、不连续分布和无沉淀析出带的宽化,使得T73时效态的腐蚀敏感性显著降低。The influences of aging treatment on corrosion behavior of A1-Zn-Mg alloy with Sc element were investigated by means of constant temperature immersion corrosion method, electrochemical polarization curves measure, slow strain rate test （SSRT）, scanning electron microscopy and transmission electron microscopy. The experimental results show that natural aging has worst exfoliation corrosion （EXCO） and intercrystalline corrosion resistance, with the corrosion susceptibility order from low to high under different aging conditions as follows： T73 temper, T6 temper, under aging, natural aging. The same trend of corrosion behavior with aging treatment is demonstrated by electrochemical polarization curves. T73 temper has low susceptibility of stress corrosion cracking （SCC） compared with T6 temper at the same strain rate. Meanwhile, the alloy is more susceptible to SCC at 1.33×10^-6s^-1 than at 6.67×10^-6s^-1 at the same aging temper. The corrosion susceptibility of Al-Zn-Mg alloy with Sc element is related to the sizes and distribution of precipitated phase （MgZn2） and precipitate free zone （PFZ） at grain boundaries. Under T6 temper, due to the continuous chain distribution of precipitated phase at grain boundary, the corrosion susceptibility of the alloy is high. On the contrary, with the equilibrium phases discontinuous and PFZ widening, T73 temper can decrease corrosion susceptibility of the alloy.

关 键 词：含钪Al-Zn-Mg-Zr合金 时效处理 剥落腐蚀 晶间腐蚀 极化曲线 应力腐蚀 

分 类 号：TG174.3[金属学及工艺—金属表面处理]