(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) 有色金屬材料科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
3. 中國兵器科學(xué)研究院 寧波分院，寧波 315103)
摘 要: 利用金相顯微鏡(OM)、掃描電鏡(SEM)、能譜分析(EDS)、X射線衍射分析、集氣法及動(dòng)電位極化曲線研究了微量Er對鑄態(tài)AZ91鎂合金顯微組織和腐蝕性能的影響。結(jié)果表明：微量Er可細(xì)化AZ91鎂合金的鑄態(tài)組織，當(dāng)AZ91鎂合金中加入Er的含量不高于0.7%(質(zhì)量分?jǐn)?shù))時(shí)，隨著Er含量的增加，鎂合金中的γ-Mg17Al12相由粗大、連續(xù)塊狀分布逐漸轉(zhuǎn)變?yōu)榧?xì)小、島狀均勻分布，并且有Al3Er相生成；同時(shí)，微量Er也可顯著提高鑄態(tài)AZ91的耐腐蝕性能，當(dāng)Er含量為0.7%時(shí)，合金耐蝕性能大幅度提高，在3.5%(質(zhì)量分?jǐn)?shù))NaCl水溶液中浸泡的腐蝕速率為0.546 06 mg/(cm2·d)，僅為常規(guī)AZ91鎂合金的1/15；微量Er使得AZ91鎂合金在3.5% NaCl溶液中的自腐蝕電位升高，自腐蝕電流降低，從而提高AZ91鎂合金的耐腐蝕性能。
關(guān)鍵字: AZ91鎂合金；Er；顯微組織；腐蝕性能
AZ91 magnesium alloy
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Ningbo Branch, Ordnance Science Institute of China, Ningbo 315103, China）
Abstract: The microstructure and corrosion behavior of AZ91 magnesium alloys with trace addition of Er were investigated by optical microscopy (OM), scanning electronic microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffractometry (XRD), collecting gas, immersion test and potention dynamic polarization. The results show that with Er addition in the range of 0%−0.7% (mass fraction), the γ-Mg17Al12 phase is refined with increasing Er addition and disperses well in the matrix, and Al3Er phase forms. The corrosion resistance of alloy is significantly improved. The alloy with 0.7% Er has the best corrosion resistance, and the corrosion rate is 0.546 06 mg/(cm2·d), only 1/15 of that of common AZ91 alloy. Trace addition of Er enhances the electrode voltage and lowers the corrosion current of AZ91 alloy in 3.5% NaCl solution, thus improves the corrosion characters of magnesium alloy.
Key words: AZ91 magnesium alloy; Er; microstructure; corrosion resistance
