(1. 東北輕合金有限責(zé)任公司，哈爾濱 150060；
2. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083)
摘 要: 采用透射電鏡觀察、剝落腐蝕實(shí)驗(yàn)以及慢應(yīng)變速率拉伸實(shí)驗(yàn)研究時(shí)效處理制度對(duì)7A55合金預(yù)拉伸板材析出相特征、電導(dǎo)率和腐蝕性能的影響。結(jié)果表明：在T651峰時(shí)效態(tài)，7A55合金的晶內(nèi)析出相主要為細(xì)小、彌散分布的GP區(qū)和η′相，晶界析出相呈連續(xù)分布，在T651狀態(tài)合金雖然具有最高強(qiáng)度，但剝落腐蝕傾向嚴(yán)重，應(yīng)力腐蝕敏感性最大；T7351時(shí)效態(tài)晶內(nèi)析出相主要為短棒狀的粗大η相，晶界析出物呈粗大、非連續(xù)分布，此時(shí)雖然耐腐蝕性能最好，但強(qiáng)度損失很大；T7651、T7451時(shí)效態(tài)晶內(nèi)既存在與基體半共格的η′相，又存在與基體不共格的η相，晶界析出相比較粗大且析出相之間的間距增大，呈斷續(xù)分布，因此，在T7651和T7451狀態(tài)，合金強(qiáng)度損失不大，而耐蝕性得到明顯改善。
關(guān)鍵字: 7A55合金；雙級(jí)時(shí)效；微觀組織；剝落腐蝕；應(yīng)力腐蝕；電導(dǎo)率
corrosion behavior of 7A55 alloy plate
（1. Northeast Light Alloy Co., Ltd., Harbin 150060, China;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The effects of aging treatments on the microstructure, corrosion resistance and electrical conductivity of pre-stretched 7A55 alloy plate were investigated by transmission electron microscopy(TEM) and slow strain rate tension test. The results show that in T65l condition the main precipitates are GP zones and η′ phase in the matrix, and the grain boundary precipitates distribute continuously. In T651 condition the strength of 7A55 alloy plate is the highest; however the alloy has a serious tendency to exfoliation corrosion and very high sensitivity to stress corrosion crack. In T7351 condition the coarse rod-like η precipitates are mainly observed in the matrix and the grain boundary precipitates are coarse obviously and distribute sparsely. So, the corrosion resistance is the highest but the strength decreases to the lowest level. In T7651 and T7451 conditions, both η′ and η precipitates exist in the matrix, and the coarse and isolate precipitates present in the grain boundaries, which contributes to the improvement of the corrosion resistance and electrical conductivity, while the decrease of tensile strength is small.
Key words: 7A55 alloy plate; double aging; microstructure; exfoliation corrosion; stress corrosion; electrical conductivity
