Modification of Mg₂Si morphology in Mg–Si alloys with Bi

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• 作者：E.J. Guo ; B.X. Ma ; L.P. Wang
• 关键词：Modification ; Magnesium ; Microstructure ; Mg₂Si ; Bismuth
• 刊名：Journal of Materials Processing Technology
• 出版年：2008
• 期刊代码：102_09240136
• 类别：et
• 出版时间：12 September 2008
• 卷：206
• 期：1-3
• 页码：161-166
• 文件大小：1026 K

摘要

The effect of bismuth (Bi) addition on primary Mg₂Si phases in Mg–Si alloys was investigated. It is found that proper amount of Bi in the alloys is efficient in refining the microstructure of Mg–Si alloys. According to the present experiment, the optimal modification effect is obtained when the Bi content in the alloy is 0.5%. The size of primary Mg₂Si is significantly decreased to 15 μm or less, and its morphology is changed from coarse dendritic shape to polyhedral shape. However, when the Bi content is increased to or exceeds 0.8%, it is found that many primary Mg₂Si become coarse again. Moreover, a small amount of Mg–Bi intermetallic compounds in the form of Mg₃Bi₂ are formed in the eutectic microstructure of the alloys with 0.5, 0.8 and 1%Bi.