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Grain Refining Mechanisms of Magnesium Alloy by Superheat-treating

镁合金过热处理晶粒细化机理

基本信息

批准号：
12650738
负责人：
MOTEGI Tetsuichi
金额：
$ 2.24万
依托单位：
Chiba Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650738/
关键词：
Gas-Liquid Multi-phase flow Liquid-Licquid Multiphase flow Boundary Phenomena PTV Measurement Tele-Cntric Lens Deformation of Bubbles Collision of Bubbles 核生成マグネシウム合金過熱処理異質核

项目摘要

The most popular grain refiner consisting of C_2 CI_6 was used in industry for grain refining of magnesium alloy containing an aluminum element. However, it has a great problem, because it generate the dyoxine matter by the decomposition of chloride. At present, it cannot use at all. On the other hand, it is well known that the superheat treatment is effective for grain refining of Mg-AI system alloys, however, the grain refining mechanism is not clarified yet. The advantage of this method keeps clean the environment, because harmful grain refiners such as C_2 CI_6 were not used so that it is useful technology, except the larger thermal energy is consumed because of the high temperature.The purpose of this investigation is to clarify the grain refining mechanisms of the superheat-treated AZ 91 magnesium alloy. The molten alloys were quenched at various temperatures and cast into the mold after superheat treatment. Each sample reveals each high temperature state as quenched. Each sample is examined by an optical microscope and EPMA. The primary magnesium dendrites were generated from the heterogeneous nuclei of AI_4 C_3. The impurity elements in the magnesium alloy such as Mn, Fe, Si, and Cu were melted in the molten magnesium alloy, however, C was remained in the superheat treated molten alloy. In this process, C and AI reacted and formed AI_4 C_3. High purity Mg-AI alloy was also cast with and without superheat treatment. Both samples were refined for the grains because the AI_4 C_3 compounds were able to form easily without the superheat treatment. It is concluded that the AI_4 C_3 compounds in the commercial AZ91 alloy were formed during the superheat-treatment and they nucleated the primary crystals of magnesium.

工业上最常用的C2Cl6细化剂用于含铝镁合金的细化。然而，它有一个很大的问题，因为它是通过分解氯离子产生二恶英物质的。目前，它根本不能使用。另一方面，众所周知，过热处理对镁铝系合金的晶粒细化是有效的，但其细化机理尚不清楚。这种方法的优点是没有使用C2 Cl6等有害细化剂，是一种有用的技术，只是由于温度高消耗了较大的热能。本研究旨在阐明过热处理AZ91镁合金的细化机理。熔融的合金在不同的温度下淬火，过热处理后浇注到模具中。每个样品都显示出淬火的每一种高温状态。每个样品都用光学显微镜和电子探针进行检查。初生镁枝晶是由Al_4C_3的非均质晶核生成的。镁合金中的杂质元素如锰、铁、硅和铜在镁合金熔体中熔化，而碳则留在过热处理的熔体中。在这个过程中，C和Al反应生成了Al_4C_3。在此过程中还铸造了高纯镁铝合金，并对其进行了过热处理。由于Al_4C_3化合物在没有过热处理的情况下很容易形成，所以两种样品都被细化为颗粒。结果表明，工业AZ91合金中的Al_4C_3化合物是在过热处理过程中形成的，它们形核了镁的初晶。