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時效制度對7A55合金微觀組織與腐蝕性能的影響時效制度對7A55合金微觀組織與腐蝕性能的影響Effect of aging treatments on microstructure and corrosion behavior of 7A55 alloy plate 采用透射電鏡觀察、剝落腐蝕實驗以及慢應變速率拉伸實驗研究時效處理制度對7A55合金預拉伸板材析出相特征、電導率和腐蝕性能的影響。結果表明：在T651峰時效態(tài)，7A55合金的晶內析出相主要為細小、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度，但剝落腐蝕傾向嚴重，應力腐蝕敏感性最大；T7351時效態(tài)晶內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，此時雖然耐腐蝕性能最好，但強度損失很大；T7651、T7451時效態(tài)晶內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)，合金強度損失不大，而耐蝕性得到明顯改善。 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. 下一篇： 2D70耐熱鋁合金顯微組織均勻化熱處理
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