(1. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410082;
2. 南南鋁業(yè)股份有限公司，南寧 530031;
3. 北京航空材料研究院，北京 100095)
摘 要: 采用拉伸試驗、晶間腐蝕實驗、透射電鏡觀察等方法，研究時效工藝對7A85鋁合金顯微組織、力學(xué)性能和晶間腐蝕行為的影響。結(jié)果表明:7A85鋁合金的T6態(tài)晶內(nèi)分布著大量細(xì)小而彌散的GP區(qū)和少量η′相，晶界上析出相(η相)連續(xù)分布，無明顯的無沉淀析出帶(PFZ);T73態(tài)晶內(nèi)析出相尺寸和間距都變大，晶界析出相長大粗化、呈不連續(xù)分布，PFZ帶寬化，具有良好的抗晶間腐蝕性能，但強(qiáng)度略低;回歸再時效處理后的7A85鋁合金具有與T6態(tài)相似的晶內(nèi)組織和與T73態(tài)相似的晶界組織，合金的抗拉強(qiáng)度及電導(dǎo)率分別為731.7MPa和36.5%(IACS)，即合金同時具有較好的強(qiáng)度和抗腐蝕性能。合金的晶間腐蝕敏感性與晶界析出相和無沉淀析出帶有關(guān)，晶界析出相尺寸越大，分布越不連續(xù)，PFZ 越寬，合金腐蝕敏感性越小。
關(guān)鍵字: 7A85鋁合金;時效硬化;顯微組織;晶間腐蝕
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Alnan Aluminum Co., Ltd., Nanning 530031, China;
3. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:The influence of aging process on mechanical properties and intergranular corrosion of 7A85 aluminum alloy was investigated by tensile testing and intergranular corrosion testing combining with transmission electron microscope. The results show that, a large quantity of GP zones and some η′ phases disperse in grain, with continuous secondary phases in grain boundary, and the precipitation free zone (PFZ) does not exist in the T6 temper. 7A85 aluminum obtains a favorable corrosion property with the phases in the grain boundary becoming discontinuous and PFZ widening in the T73 temper. 7A85-RRA, which has the T6-like grain-interior and the T73-like grain-boundary morphology, shows good comprehensive performance, with the combinations of tensile strength of 731.7 MPa and electrical conductivity of 36.5%(IACS). Corrosion sensibility of alloy is related to the characteristics of equilibrium phase and precipitation free zone at grain boundary, with the equilibrium phases discontinuous and PFZ widening, the corrosion sensibility of alloy decreases.
Key words: 7A85 aluminum alloy; age hardening; microstructure; intergranular corrosion
