Modification of Mg₂Si in Mg-Si alloys with gadolinium

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• 作者：Lingying Ye ; Jilong Hu ; ^{hjlong@csu.edu.cn} ; ^{hjlong6688@sina.com} ; Changping Tang ; Xinming Zhang ; Yunlai Deng ; Zhaoyang Liu ; Zhile Zhou
• 关键词：Modification ; Mg&ndash ; Si alloy ; Mg2Si ; Gd
• 刊名：Materials Characterization
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：79
• 期：Complete
• 页码：1-6
• 全文大小：1525 K

文摘

The modification effect of gadolinium (Gd) on Mg₂Si in the hypereutectic Mg-3 wt. % Si alloy has been investigated using optical microscope, scanning electron microscope, X-ray diffraction and hardness measurements. The results indicate that the morphology of the primary Mg₂Si is changed from coarse dendrite into fine polygon with the increasing Gd content. The average size of the primary Mg₂Si significantly decreases with increasing Gd content up to 1.0 wt. % , and then slowly increases. Interestingly, when the Gd content is increased to 4.0 and 8.0 wt. % , the primary and eutectic Mg₂Si evidently decrease and even disappear. The modification and refinement of the primary Mg₂Si is mainly attributed to the poisoning effect. The GdMg₂ phase in the primary Mg₂Si is obviously coarsened as the Gd content exceeds 2.0 wt. % . While the decrease and disappearance of the primary and eutectic Mg₂Si are ascribed to the formation of vast GdSi compound. Therefore, it is reasonable to conclude that proper Gd (1.0 wt. % ) addition can effectively modify and refine the primary Mg₂Si.