(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2. 中南大學(xué) 輕合金研究院，長沙 410083；
3. 中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點實驗室，長沙 410083)
摘 要: 借助掃描電子顯微鏡(SEM)和X射線衍射(XRD)對AZ31-xCu(x=0，0.5，1.5，3，質(zhì)量分?jǐn)?shù)，%)合金的鑄態(tài)組織、相結(jié)構(gòu)及表面腐蝕形貌進(jìn)行測試和分析。采用浸泡試驗和電化學(xué)試驗對研究合金在3.5%氯化鈉溶液中的腐蝕行為進(jìn)行系統(tǒng)地對比研究。結(jié)果表明：隨銅含量的增加，研究合金中的主要第二相AlCuMg相遞增；腐蝕過程的主要腐蝕機(jī)制是微電偶腐蝕，AlCuMg相作為微電偶腐蝕陰極與鎂基體陽極構(gòu)成微電偶腐蝕對，隨AlCuMg相體積分?jǐn)?shù)增加，形成的微電偶腐蝕對增多，相應(yīng)的腐蝕速率增大。當(dāng)銅含量為3%時，研究合金的腐蝕速率最大，研究合金的析氫速率和腐蝕電流密度分別為：75？mL/(cm2？d)和698？μA/cm2。
關(guān)鍵字: AZ31-xCu合金；AlCuMg相；腐蝕速率；微電偶腐蝕陰極；鎂基體陽極
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Light Alloy Research Institute, Central South University, Changsha 410083, China;
3. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China）
Abstract:The as-cast microstructure, phase composition and surface corrosion morphologies of AZ31-xCu(x=0, 0.5, 1.5, 3, mass fraction, %) alloys were observed by scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS) and X-ray diffraction (XRD). The corrosion behavior of the alloys in 3.5% NaCl solution was investigated by immersion test and electrochemical test. The results indicate that the content of AlCuMg phase, main secondary phase in the Cu-containing alloys, is positively dependent on copper concentration. Acceleration of corrosion rate is found in Cu-containing alloys due to micro-galvanic corrosion. AlCuMg phase acts as micro-galvanic cathode against anodic magnesium matrixes. The corrosion rate of the alloy with Cu content of 3% is the fastest. The AZ31-3Cu alloy exhibits the maximum hydrogen evolution rate of 275？mL/(cm2？d-1) and corrosion current density of 698？μA/cm2.
Key words: AZ31-xCu alloy; AlCuMg phase; corrosion rate; micro-galvanic cathode; anodic magnesium matrixe
