Cu及热处理制度对Al—Mg—Si系合金晶间腐蚀敏感性的影响

采用浸泡腐蚀实验和电化学实验研究了强化元素Cu含量的改变及不同时效制度对Al-Mg-Si合金晶间腐蚀敏感性的影响，并利用XRD和SEM对腐蚀产物的构成及形貌进行了分析与观察，浸泡腐蚀实验结果表明：在峰时效的状态下，在0.5%Cu以上的合金中可观察到明显的晶间腐蚀而且随着Cu含量的增加，合金最大腐蚀深度增加；在欠时效状态下，1%Cu以上的合金中观察到了微弱的晶间腐蚀；在过时效状态下，所有实验合金均只出现点蚀，电化学实验结果表明：随着Cu含量的增加，合金的Ψcorr向正的方向变化，Jcorr增加，欠时效状态下的Ψcorr比峰时效状态下的负，腐蚀电流密度较小。

Effects of Cu and age treatment on susceptibility to intergranular corrosion of Al-Mg-Si alloys

By the immersion corrosion tests and electrochemistry tests, the effects of changing Cu content and varying age treatments on the susceptibility to intergranular corrosion of Al-Mg-Si alloys have been studied. Phase structures of corrosion products were analyzed by XRD and the corrosion morphologies were observed by SEM.The results of immersion corrosion tests show that obvious intergranular corrosion is detected on the alloys with over 0.5%Cu and the maximum corrosion depth increases with increasing Cu content after the precipitation treatment. Slight intergranular corrosion is found on the alloys with over 1%Cu after the under-aged treatment. Pitting is observed on all alloys after the over-aged treatment. Results of electrochemistry tests indicate that φcorr varies to positive and Jcorr increases with increasing Cu content. The φcorr and Jcorr under the under-aged condition are more negative and smaller respectively than those under the precipitation-age condition.