(北京工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，北京 100124)
摘 要: 通過晶間腐蝕實(shí)驗(yàn)、剝落腐蝕實(shí)驗(yàn)和電化學(xué)測(cè)試，結(jié)合光學(xué)顯微鏡、掃描電鏡和透射電鏡等分析手段，研究高鋅超高強(qiáng)鋁合金在不同時(shí)效狀態(tài)下的腐蝕行為。結(jié)果表明：雙級(jí)過時(shí)效和回歸再時(shí)效可提高合金的抗腐蝕能力，在3.5%NaCl(質(zhì)量分?jǐn)?shù))溶液中測(cè)試的極化曲線也表現(xiàn)出相同的趨勢(shì)。晶界析出相尺寸和形態(tài)是影響合金腐蝕性能的主要因素。雙級(jí)過時(shí)效和回歸再時(shí)效可使晶間析出相粗化且呈斷續(xù)分布，使腐蝕不能連續(xù)發(fā)展，從而提高合金的耐蝕性能。超高強(qiáng)鋁合金在含Cl-介質(zhì)中腐蝕的發(fā)展動(dòng)力學(xué)過程分為點(diǎn)蝕、晶間腐蝕和剝落腐蝕3個(gè)階段。
關(guān)鍵字: 高鋅超高強(qiáng)鋁合金；晶間腐蝕；剝落腐蝕；極化曲線；晶界析出相
（School of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China）
Abstract:The influence of aging treatment on the intergranular corrosion and exfoliation corrosion susceptibility of the high Zn content super-high strength Al alloy was studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission election microscopy (TEM). The results show that the two-stage over-aging treatment and retrogression and re-aging treatment can improve the corrosion resistance of the super-high strength Al alloy, which are in accord with the results of polarization tests in 3.5%NaCl (mass fraction) solution. TEM observation shows that the size and morphology of precipitates at grain boundaries are the key factors responsible to the corrosion behavior of the alloy. After the two-stage over-aging treatment and retrogression and re-aging treatment, the precipitates at grain boundaries are coarse and discontinuous, which decreases the corrosion susceptibility of the alloy. Moreover, there are three stages of the corrosion development of the super-high strength Al alloy studied in Cl--containing media as pitting, intergranular corrosion and exfoliation corrosion.
Key words: high Zn content super-high strength Al alloy; intergranular corrosion; exfoliation corrosion; polarization curve; grain boundary precipitation
