铸造AZ91镁合金在CO_3^(2-)/HCO_3^-体系中的应力腐蚀行为  

STRESS CORROSION CRACKING BEHAVIORS OF AS-CAST AZ91 MAGNESIUM ALLOY IN CO_3^(2-)-/HCO_3^-SOLUTIONS

作　　者：黄发[1] 陈健[1] 王俭秋[1] 

机构地区：[1]中国科学院金属研究所金属腐蚀与防护国家重点实验室,沈阳110016

出　　处：《中国腐蚀与防护学报》2010年第5期347-353,共7页Journal of Chinese Society For Corrosion and Protection

基　　金：国家自然科学基金项目(50499336)资助

摘　　要：用电化学实验、浸泡实验与慢应变速率拉伸实验研究铸造AZ91镁合金在不同浓度比例的CO_3^(2-)/HCO_3^-溶液体系中的应力腐蚀(SCC)行为。结果表明,随着溶液pH值的升高,AZ91镁合金的应力腐蚀敏感性降低。点蚀是AZ91镁合金在该实验体系下的裂纹萌生源,随着实验时间的延长,萌生于点蚀底部的微裂纹会逐渐扩展形成主裂纹,主裂纹靠吞并其前端的微裂纹向前扩展,直至发生SCC失效。The stress corrosion cracking（SCC） behaviors of as-cast AZ91 magnesium alloy in CO_3^（2-）/HCO_3^- solutions were investigated by electrochemical test,immersion test and slow strain rate test（SSRT） respectively. The results showed that the stress corrosion cracking sensitivity of as-cast AZ91 alloy in CO_3^（2-）/HCO_3^- solutions decreased with the increase of pH values of the solutions.The surface was covered by a film mainly composed of Mg（OH）_2 and Al（OH）_3.Al（OH）_3 could be dissolved in alkaline solutions and AlO_2^- engendered.Pitting was the main crack source of AZ91 alloy in such solutions.The cracking ofβphase also resulted in microcracks in the matrix.Microcracks initiating at the bottom of pitting combined into a main crack.The main crack propagated by coalescence of the existing microcracks ahead until the SCC fracture occurred.

关 键 词：AZ91镁合金 应力腐蚀开裂 CO3^2-/HCO3^-溶液 

分 类 号：TG172.6[金属学及工艺—金属表面处理]