(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙410083；
2. 中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室，長沙410083；
3. 中南大學(xué) 輕質(zhì)高強(qiáng)結(jié)構(gòu)材料國防科技重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
4. 中南大學(xué) 有色金屬先進(jìn)結(jié)構(gòu)材料與制造協(xié)同創(chuàng)新中心，長沙 410083)
摘 要: 采用慢應(yīng)變速率拉伸(SSRT)試驗(yàn)、金相顯微鏡(OM)、掃描電鏡(SEM)和透射電鏡(TEM)等手段研究了微量元素Ge對7020鋁合金板材應(yīng)力腐蝕斷裂敏感性的影響。通過比較不含Ge和含Ge板材中晶內(nèi)η′強(qiáng)化相尺寸與體積分?jǐn)?shù)的差異分析了合金強(qiáng)度下降的原因；通過比較不含Ge和含Ge板材中晶粒組織和晶界η相的尺寸、間距及化學(xué)成分的差異分析了合金應(yīng)力腐蝕斷裂敏感性下降的原因。結(jié)果表明：加入Ge元素后，板材SSRT的抗拉強(qiáng)度更低，在NaCl溶液中的強(qiáng)度和伸長率較空氣中的下降率也更低，應(yīng)力腐蝕指數(shù)由0.059減小至0.017，應(yīng)力腐蝕斷裂敏感性明顯降低。
關(guān)鍵字: 7020鋁合金；Ge；應(yīng)力腐蝕斷裂；顯微組織
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
3. The National Key Laboratory of Science and Technology for National Defence on High-strength Lightweight Structural Materials, Central South University, Changsha 410083, China;
4. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083, China）
Abstract:The effect of minor Ge on susceptibility to stress corrosion cracking (SCC) of 7020 aluminium alloy sheet was investigated by slow strain rate tensile (SSRT) test, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The reason for the decreased strength of 7020-Ge sheet was discussed according to the change of the size and volume fraction of η′ strengthening phase inside grains, and the reason for the decreased SCC susceptibility was discussed according to the change of grain structure, and the size, spacing, chemical compositions of η phase at grain boundaries caused by Ge addition. The results show that, after the introduction of Ge, the ultimate strength of sheets subjected to SSRT test decreases; moreover, the decrement of strength and elongation in NaCl solution compared with air decreases, and ISSRT decreases from 0.059 to 0.017, indicating significantly decreased SCC susceptibility.
Key words: 7020 aluminium alloy; Ge; Stress corrosion cracking; microstructure
