(1. 常州大學 材料科學與工程學院，常州 213164；
2. 常州大學 常州市先進金屬重點實驗室，常州 213164;
3. 中南大學 材料科學與工程學院，長沙 410083)
摘 要: 采用光學顯微鏡、透射電鏡、X射線衍射、掃描電鏡及能譜等研究中性和酸性NaCl腐蝕溶液中殘留結(jié)晶相對Al-Mg-Si-Cu合金晶間腐蝕行為的影響。結(jié)果表明：實驗合金含有Mg2Si和Al4.01(MnFeCrCu)Si0.74兩種殘留結(jié)晶相。在中性和酸性溶液中，Mg2Si相通過Mg優(yōu)先溶解，由陽極轉(zhuǎn)換成陰極，進而造成基體點蝕。Al4.01(MnFeCrCu)Si0.74相在中性溶液中作為陰極，導致周圍Al基體發(fā)生點蝕，而在酸性溶液中只發(fā)生自身腐蝕。當點蝕發(fā)生在晶界上時，能直接誘發(fā)晶間腐蝕；而當點蝕發(fā)生在晶內(nèi)時，則需點蝕擴展至晶界才能誘發(fā)晶間腐蝕。不同于中性溶液，酸性溶液中的晶間腐蝕也可以由晶界直接形成。
關(guān)鍵字: Al-Mg-Si-Cu合金；結(jié)晶相；優(yōu)先溶解；晶間腐蝕；點蝕
（1. School of materials science and engineering, changzhou university, changzhou 213164, China;
2. Key Laboratory of Advanced Metals of changzhou, changzhou university, changzhou 213164, China;
3. School of materials science and engineering, central south university, changsha 410083, China）
Abstract:The optical microscopy, transmission electron microscopy (TEM), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectrum (EDS) were employed to study the effect of residual constituents on the intergranular corrosion (IGC) behavior of Al-Mg-Si-Cu alloy in the neutral and acidic solutions. The results show that the alloy includes two types of constituent phases, Mg2Si and Al4.01(MnFeCrCu)Si0.74. In the neutral and acidic solutions, the anodic Mg2Si phase first undergoes the preferential dissolution of Mg and converts into the cathodic one, which gives rise to the point corroding of adjacent matrix. The Al4.01(MnFeCrCu)Si0.74 phase leads to the anodic dissolution of matrix at its adjacent periphery in the neutral solution. But the self-corrosion of Al4.01(MnFeCrCu)Si0.74 occurs in the acidic solution. It is the pitting corrosion occurring at the grain boundary that can directly induce IGC. However, IGC does not occur until the pit grows up and contacts with the grain boundary when the pits are in the grain interior. Besides, unlike the corrosion behavior of alloy in the neutral solution, IGC can occur spontaneously by grain boundary in the acidic condition.
Key words: Al-Mg-Si-Cu alloy; constituents; preferential dissolution; intergranular corrosion; pitting corrosion
