(1. 湖南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410082； 2. 南車青島四方機(jī)車車輛股份有限公司，青島 266111)
摘 要: 研究了峰值時(shí)效狀態(tài)下，不同Zn、Mg含量(質(zhì)量分?jǐn)?shù))對(duì)高Cu含量(2.0%~2.5%)的Al-Zn-Mg-Cu合金耐局部腐蝕能力的影響，利用透射電鏡和掃描電鏡表征了合金局部腐蝕行為與其微觀結(jié)構(gòu)之間的關(guān)系。結(jié)果表明：對(duì)Mg含量不同的兩組目標(biāo)合金，Zn含量降低，合金的耐局部腐蝕能力變差；對(duì)應(yīng)比較Mg含量不同的兩組合金，初始階段低Mg組合金的耐晶間腐蝕能力較差，但深度發(fā)展階段低Mg組合金的耐晶間腐蝕能力較好；前期階段高M(jìn)g組合金的耐剝蝕能力較好，但后期深度腐蝕階段，高M(jìn)g組合金的耐剝蝕能力變得較差。
關(guān)鍵字: Al-Zn-Mg-Cu合金；局部腐蝕；微觀組織；晶界無(wú)沉淀析出帶；連續(xù)體顆粒
（1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China; 2. CSR Qingdao Sifang Locomotive and Rolling Stock Co., Ltd., Qingdao 266000, China）
Abstract:It has generally been believed that the Cu addition in Al-Zn-Mg-Cu alloys can improve the stress corrosion resistance of the alloys. Nonetheless, for such alloys with a high Cu-content, few papers have paid attention to their exfoliation corrosion (EXCO) and intergranular corrosion (IGC) (two kinds of localized corrosion) resistance in relation with their Zn and Mg contents. In the present study, peak-aged Al-Zn-Mg-Cu alloys with relatively high Cu contents (2.0%-2.5%) were studied for their localized corrosion behaviors with varying Zn and Mg contents. By scanning/transmission electron microscopy (S/TEM), the microstructures of the alloys were characterized in relation with their properties of corrosion resistance. The alloys were classified into two groups: one with higher Mg content (high-Mg group) and another with lower Mg content (low-Mg group). The results show the following: 1) For both the two groups of alloys, with decreasing the Zn-content, their localized corrosion resistance decreases without exception; 2) The high-Mg group of alloys are worse than the low-Mg group of alloys in IGC resistance in their initial stages of corrosion, but better in their late stages; 3) For EXCO resistance, the former group is better than the late group in their early-stages of corrosion, but worse in their late stages of in-depth corrosion.
Key words: Al-Zn-Mg-Cu alloys; localized corrosion; microstructure; precipitate free zone; constituent
