The influences of two kinds of casting modules of metal casting (MC) and expandable pattern casting (EPC) on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electron microscopy (SEM) observation, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. It is found that the quantity of the Mg24 (Gd, Y)5 phase in MC is more than that in EPC due to the cooling rate. There is more alloying element dissolved in the matrix compared with MC. For EPC, the galvanic corrosion effect between the matrix and the Mg24 (Gd, Y)5 phase decreases and the corrosion resistance increases compared with the MC. The chief corrosion mode for Mg-11Gd-3Y alloy is pitting corrosion because most of the alloying elements are transformed into intermetallic phases. The average corrosion rate of the MC alloy in the immersion test is five times higher than that of EPC alloy and yttrium is present in the product film, which will provide increased protection for Mg-11Gd-3Y alloy. The electrochemical measurements and immersion test show that the EPC process increases the corrosion resistance compared with the MC Mg-11Gd-3Y alloy.%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.
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