The relation between microstructure and corrosion behavior of Mg-Y-RE-Zr alloys
The relation between microstructure and corrosion behavior of Mg-Y-RE-Zr alloys
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DOI：
10.1016/j.jallcom.2006.05.075
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发表时间：
2007-04-04
影响因子：
6.2
通讯作者：
Cohen, S.
中科院分区：
文献类型：
--
作者：
Ben-Hamu, G.;Eliezer, D.;Cohen, S.
采用动电位极化曲线和俄歇电子能谱研究了不同热处理工艺的砂型铸造Mg-Y-RE-Zr合金在饱和Mg（OH）2的3.5%NaCl溶液（pH 10.5）中的腐蚀性能。对Mg-Y-RE-Zr合金经不同热处理后的显微组织进行了分析。结果发现，该合金的晶粒内的中心富锆区域比晶粒的外部贫锆区域更耐腐蚀。通过对合金的腐蚀过程、极化行为和显微组织的分析，得出锆对合金耐蚀性的改善作用是多方面的，主要结果表明：锆的加入细化了合金的晶粒，显著提高了合金的耐蚀性。不同的热处理工艺可以控制其显微组织。由于时效时间的不同，析出相有两种不同的分布形式：一种位于晶粒中心，另一种则呈随机分布。富含锆的晶粒中心比晶粒的贫锆边缘区域表现出更好的耐腐蚀性。Mg-Y-RE-Zr合金在250 ℃时效3 h后的腐蚀速率与其他时效时间相比，降低了100%以上。(c)2006 Elsevier B. V.保留所有权利。
Corrosion performance of sand cast Mg-Y-RE-Zr alloy after different heat-treatments was investigated in 3.5% NaCl solution saturated with Mg(OH)(2) (pH 10.5) using potentio-dynamic polarization and Auger electron spectroscopy. Microstructure analyses have been carried out on the Mg-Y-RE-Zr alloy after different heat-treatments. It was found that the central zirconium-rich areas within the grains of the alloy were more corrosion resistant than the outer zirconium-depleted areas of the grains. Based on the analyses of the corrosion process, polarization behavior and the microstructure of the alloy, it is concluded that zirconium acts in a number of ways to improve corrosion resistance.Our main results show that when zirconium is added to refine the grain size, the corrosion resistance of the alloy is significantly improved. The microstructure is controlled by different heat-treatments. Due to different aging time two different precipitates: were one located in grain center and the other distributed randomly. Grain centers, rich of zirconium, exhibit a better corrosion resistance than the zirconium-depleted edge areas of the grains. The corrosion rate of the Mg-Y-RE-Zr alloys after 3 h aging in 250 degrees C, to comparison the others aging times, decreasing by more than 100%. (c) 2006 Elsevier B.V. All rights reserved.