时效处理对Mg-Y合金腐蚀行为和腐蚀机理的影响

摘要

This paper studied the influence of aging treatment on the corrosion behavior and mechanism of Mg-Y alloys with different Y content through corrosion mass loss test, electrochemical test and corrosion morphologies observation. Results show that the peak-aging times of Mg-(0.25, 2.5, 5, 8 and 15) Y alloys at 250 ℃C were 4, 6, 10, 12 and 16 h. The aging treatment reduced the corrosion resistance of Mg-Y alloys, and the corrosion resistance of Mg-Y alloys became worse with increasing of the aging time. The change magnitude of the open circuit potentials for Mg-(0.25, 2.5)Y alloys was greater than that of Mg-(5, 8 and 15)-Y alloys. The polarization curves of Mg (0.25, 2.5, 5, 8 and 15) Y alloys had the similar shape after aging treatment, and the slopes of the anodic branch were greater than those of the cathodic branches. After aging treatment, the corrosion modes of Mg-0.25Y and Mg-(2.5, 5, 8 and 15) Y alloys were uniform corrosion and pitting corrosion with small local deep corrosion.%本文采用腐蚀失重试验、电化学测试和腐蚀形貌观察等研究方式研究了时效处理对不同Y含量Mg-Y 合金的腐蚀行为和腐蚀机理的影响机制.研究结果表明:Mg-(0.25,2.5,5,8,15)Y 合金在250 ℃C时的峰时效时间分别为4、6、10、12和16 h;时效处理降低了Mg-Y合金的耐腐蚀性能,并且对于同一种Mg-Y合金的耐蚀性能随着失效时间的延长而逐渐降低;Mg-(0.25, 2.5)Y合金的开路电位的变化幅度远大于Mg-(5,8,15) Y合金的开路电位的变化幅度;时效处理后,Mg-(0.25,2.5,5, 8,15)Y这5种合金有着相类似的极化曲线形状,并且阳极曲线的斜率均大于阴极曲线的斜率;时效处理后,Mg-0.25Y合金的腐蚀机理为均匀腐蚀,而Mg-(2.5,5,8,15)Y合金的腐蚀机理为局部腐蚀较深的点蚀.