固溶时效处理对AZ31-0.6Sr镁合金腐蚀性能的影响
Effects of Solution and Aging Treatment on Corrosion Resistance of AZ31-0.6Sr Alloy
刘军威1, 彭晓东1,2, 刘明朴1
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作者单位：1.重庆大学 材料科学与工程学院, 重庆 400044; 2. 重庆大学 国家镁合金材料工程技术研究中心, 重庆 400044
中文关键字：腐蚀； 时效； 固溶； 镁合金； 极化曲线
英文关键字：corrosion; aging treatment; solution treatment; magnesium alloy; polarization curves
中文摘要：采用盐水浸泡试验研究了铸态(F)、500 ℃固溶(T4)和250 ℃时效16 h(T5)的AZ31-0.6Sr镁合金在w(NaCl)=3.5%溶液中的腐蚀行为。结果表明，铸态镁合金耐腐蚀性能最差，T5态耐腐蚀性能有所提升，T4态合金耐腐蚀性能最好。合金腐蚀速率随热处理状态的变化与其微观组织有关，铸态合金中的富Sr化合物能与基底α相构成电偶腐蚀而加剧合金腐蚀；T5态下出现了连续分布的β相能在一定程度上起腐蚀阻挡层作用，降低合金腐蚀速率。
英文摘要：The corrosion behavior of AZ31-0.6Sr alloy as-cast(F), solution treated (T4) at 500 ℃ and aged at 250 ℃ for 16 h was investigated in 3.5%NaCl solution by immersion test. The results show that the alloy as-solution has the lowest corrosion rate, and the alloy as-cast exhibites the highest corrosion rate. The dependence of the corrosion rate of the alloy on heat treatment can be related to the change of its microstructure. The Sr-rich compound in cast alloy can induce galvanic corrosion with the adjacent matrix and thereby accelerate the corrosion process. The precipitation of coarse β phase can act as a barrier to some extent and cause a decrease of the corrosion rate.