Enhanced heterogeneous nucleation in AZ91D alloy by intensive melt shearing
Enhanced heterogeneous nucleation in AZ91D alloy by intensive melt shearing
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DOI：
10.1016/j.actamat.2009.06.052
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发表时间：
2009-09-01
期刊：
影响因子：
9.4
通讯作者：
Arumuganathar, S.
中科院分区：
文献类型：
--
作者：
Fan, Z.;Wang, Y.;Arumuganathar, S.
对工业AZ 91 D镁合金熔体进行强剪切，研究其对晶粒细化的影响。使用加压过滤技术对具有和不具有熔体剪切的合金熔体进行过滤，以浓缩潜在的成核颗粒用于电子显微镜检查。结果表明，强熔体剪切显著细化了铸态AZ 91 D合金中的Al 8 Mn 5金属间化合物和初生α-Mg相，且这种细化效果对熔体剪切不敏感，即使在长时间等温保温后仍能持续。加压过滤实验首次表明，氧化膜和皮肤由纳米级MgO颗粒密集地填充在液体基质中。强烈的熔体剪切可以有效地将这种MgO颗粒分散在整个合金熔体中。HRTEM研究和详细的晶体学分析证实，分散的MgO颗粒作为有效的异质成核位点的Al 8 Mn 5和α-Mg相。(C)2009 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Intensive melt shearing was applied to the commercial AZ91D alloy melt to investigate its effects on grain refinement. Alloy melts with and without melt shearing were also filtered using a pressurized filtration technique to concentrate the potential nucleating particles for electron microscopic examination. The results showed that intensive melt shearing resulted in significant refinement of both the Al8Mn5 intermetallics and the primary alpha-Mg phase in the as-cast AZ91D alloy, and that this grain-refining effect is insensitive to the superheat and can persist even after prolonged isothermal holding. The pressurized filtration experiments showed for the first time that oxide films and skins consist of nano-sized MgO particles populated densely in a liquid matrix. Intensive melt shearing can effectively disperse such MgO particles throughout the alloy melt. The HRTEM investigation and detailed crystallographic analysis confirmed that dispersed MgO particles act as potent heterogeneous nucleation sites for both the Al8Mn5 and alpha-Mg phase. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.