(昆明理工大学 材料科学与工程学院，昆明 650093)
摘 要: 研究Mn元素对高纯Mg-3Al(质量分数，%)合金晶粒尺寸的影响。结果表明：当合金中的Mn元素含量小于0.21%(质量分数)时，合金的晶粒尺寸变化不大；但当Mn元素含量大于0.21%时，Mn元素的存在则使合金的晶粒尺寸迅速增大；Mn元素的作用主要与影响熔体中含碳晶核的形核能力有关；当Mn元素的含量小于其溶解度时，Mn元素对含碳晶核的形核能力影响不大，但当Mn元素的含量达到或超过其溶解度时，Mn元素对含碳晶核的影响迅速增大，最终导致含碳晶核的形核能力降低，引起晶粒粗化。
关键字: 镁合金；Mn；晶粒细化；异质形核
（Faculty of Material Science and Engineering,
Kunming University of Science and Technology, Kunming 650093, China）
Abstract:The effect of Mn on the grain size of high-purity Mg-3Al (mass fraction, %) alloys was investigated. The results show that the grain sizes of high-purity Mg-3Al alloys changes little when the Mn content is lower than 0.21% (mass fraction), while the grains are coarsened when Mn content is higher than 0.21%. The effect of Mn is relative to the heterogeneous nucleation of carbon-containing cores in the melt. When Mn content is low and dissolves into the melt, the nucleating potent of carbon-containing cores would not be influenced basically. But when Mn content in the melts is close to or higher than its solubility, the nucleating potent of the cores is decreased by Mn addition, and the grains are coarsened.
Key words: magnesium alloy; Mn; grain refinement; heterogeneous nucleation
