(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 廣西南鋁加工有限公司 廣西鋁合金材料與加工重點實驗室，南寧 530031；
3. 中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點實驗室，長沙 410083)
摘 要: 本文研究了一種7XXX系鋁合金厚板T6I76、T73和T6三種時效狀態(tài)的硬度、室溫拉伸和電導(dǎo)率，并采用晶間腐蝕、剝落腐蝕、極化曲線和交流阻抗測試方法研究了其局部耐腐蝕性能。結(jié)果表明：T6I76試樣的強度和硬度與T6試樣的相當(dāng)，但局部耐腐蝕性能明顯增強，且優(yōu)于T6試樣和T73試樣的。T6I76試樣經(jīng)過預(yù)時效、淬火和低溫長時間時效處理后，晶內(nèi)沉淀強化相(η′相)特征與T6試樣相似，但強度更大；與T73試樣相比，T6I76試樣的η相中Cu含量更高、Zn含量更低、間距更大，且晶界附近無沉淀析出帶寬度更窄，這能有效地阻斷沿晶陽極溶解通道，得到更好的局部耐腐蝕性能。
關(guān)鍵字: 7XXX系鋁合金；斷續(xù)時效；力學(xué)性能；晶間腐蝕；剝落腐蝕
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Guangxi Key Laboratory of Materials and Processes of Aluminum Alloys, ALG Aluminium Inc, Nanning 530031, China;
3. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China）
Abstract:The hardness, room temperature tensile properties and electrical conductivity of a 7XXX series aluminum alloy plate in T6I76, T73 and T6 under three aging conditions were studied and the local corrosion properties of the alloy were investigated by means of intergranular corrosion tests, exfoliation corrosion tests, polarization curve and electrical impedance tests. The results show that the strength and hardness of the T6I76 sample are equivalent to those of the T6 sample, but the local corrosion resistance is significantly better than that of the T6 and T73 sample. The microstructure results of scanning transmission electron microscopy (SEM) and high-angle annular dark-field transmission electron microscopy (HAADF-TEM) show that, due to the extended pre-ageing time at relatively low temperatures, the fine and dense age-hardening η′ precipitates seemed to be identical for both T6I76 sample and T6 sample. The results have also shown that the grain boundary η phase in T6I76 temper has a higher Cu content, a lower Zn content than that in T73 temper. The width of the precipitation free zone (PFZ) near the grain boundary is narrower after interrupt ageing treatment, which can effectively block the anode dissolution, therefore a better local corrosion performance is obtained.
Key words: aluminium 7XXX alloy; interrupt aging; mechanical properties; intergranular corrosion; exfoliation corrosion
