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采用电化学测量、扫描电镜观察、X射线衍射和X射线光电子能谱分析对消失模铸造和金属型铸造Mg-11Gd-3Y镁合金的腐蚀行为的影响进行研究。由于冷却速度的差异使得消失模铸造Mg-11Gd-3Y镁合金的Mg24(Gd,Y)5相数量明显比金属型铸造Mg-11Gd-3Y镁合金的少,其固溶于基体中的合金化元素明显高于金属型铸造Mg-11Gd-3Y镁合金的。对于消失模铸造,由于Mg24(Gd,Y)5相相对较少,削弱了基体与第二相之间的电偶腐蚀效应。由于多数合金化元素以第二相存在使得这两类不同浇注模铸造的Mg-11Gd-3Y镁合金的腐蚀失效方式均为点蚀。金属型铸造Mg-11Gd-3Y镁合金的平均腐蚀速率为消失模的6倍,Y出现于合金的产物膜中,起到一定的保护作用,可提高合金的耐腐蚀性能。电化学测试和浸泡试验证明,对于Mg-11Gd-3Y镁合金,与金属型铸造相比消失模铸造可以提高合金的耐腐蚀性能。
The influence of the corrosion behavior of the lost foam casting and metal casting Mg-11Gd-3Y magnesium alloy was studied by electrochemical measurement, scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Due to the difference in cooling rate, the amount of Mg24 (Gd, Y) 5 phase in the lost foam casting Mg-11Gd-3Y magnesium alloy is obviously less than that of the metal type cast Mg-11Gd-3Y magnesium alloy, and the alloying Element is significantly higher than the metal casting Mg-11Gd-3Y magnesium alloy. For the lost foam casting, due to the relatively few Mg24 (Gd, Y) 5 phases, the galvanic corrosion effect between the matrix and the second phase is impaired. Due to the presence of most of the alloying elements in the second phase, the corrosion failure modes of these two different types of cast-molded Mg-11Gd-3Y magnesium alloys are pitting corrosion. The average corrosion rate of the cast Mg-11Gd-3Y magnesium alloy is six times that of the lost foam. Y appears in the product film of the alloy and plays a protective role to improve the corrosion resistance of the alloy. Electrochemical tests and immersion tests show that for Mg-11Gd-3Y magnesium alloy, LFC can improve the corrosion resistance of the alloy compared with the metal casting.