电磁搅拌工艺

上海大学2012-2013学年秋季学期研究生课程考试

小论文

课程名称：材料结构性能及应用课程编号： 10SAU7003

论文题目:电磁搅拌工艺制Mg-Al-Mn-Ce镁合金组织及性能研究

研究生姓名: 王晓旭学号: 12721572 论文评语:

成绩: 任课教师: 评阅日期:

电磁搅拌工艺制备Mg-Al-Mn-Ce镁合金的组

织及性能研究

摘要：高性能镁合金的开发是当前材料研究的热点之一，为制备出具有良好综合性能这类镁合金，本文研究了不同含量Ce对Mg-Al-Mn-Ce镁合金的拉伸力学性能的影响。电磁搅拌工艺处理后，通过改变Ce 的含量得到不同的抗拉强度σb，屈服强度σ0.2。

加入少量的Ce(0.5%—2%，质量分数)可明显细化。α-Mg基体，随Ce量增加，合金中的β-Mg17Al12相数量减少，且由连续网状形态变为非连续分布。同时，Ce与合金中的Al结合形成针状或杆状的A12Ce 化合物。能谱分析和液淬显微组织观察表明，组织细化机制主要归结为Ce加入引起结晶界面前沿的成分过冷，增加均质形核的数量，显微组织的改善导致了合金的力学性能和腐蚀性能明显提高。

研究结果显示：稀土元素的添加可以明显改善合金的拉伸性能。Mg-Al-Mn-Ce镁合金显微组织显示，铸态组织主要由α-Mg﹑β-Mg17Al12和Al2Ce强化相构成，添加稀土后晶粒明显细化，生成稀土镁化合物Al2Ce。所以晶界处强化相的数量与形态对合金力学性能起较大作用。由于弥散分布的高熔点热稳定的颗粒相Al2Ce存在，对晶粒起到钉扎作用，从而与未加稀土合金相比，添加稀土后合金具有更好的力学性能。关键词：电磁搅拌工艺；稀土镁合金；力学性能

Microstructure and Properties of Mg-Al-Mn-Ce Magnesium Alloy Prepared by Electromagnetic Stirring Process

Abstract：The development of high performance magnesium alloy materials is a currently hotspot, for getting good preparation of the comprehensive performance such magnesium alloy. This paper researches on the different contents of Ce on the tensile mechanical properties of Mg-Al-Mn-Ce magnesium alloy. After electromagnetic stirring treatment, through changing the content of the Ce, it can get different state of the σb, and σ0. 2.

Adding 0.5%-2%Ce(mass fraction)in AZ91 magnesium alloy can decrease obviously the α-Mg grain size. The morphology of β-Mg17Al12Phase in the alloy changed from continuous network to discontinuous one，and their amount decreased with increasing Ce content. Meanwhile，thread-like or needle-like A12Ce Phases mainly distributed at grain boundaries have been observed. EDXS and the observation of water-quenched microstructure showed that the grain refinement mechanism is attributed to the addition of Ce induced the constitution under cooling at solidification interface front，which increased the number of homogeneous nucleation. The mechanical properties and corrosion resistant performance of the alloys containing Ce were improved obviously.

The result shows, adding rare earth elements can significantly improved the tensile properties of the alloy. Mg-Al-Mn-Ce magnesium alloy microstructure showed, casting organization mainly consist of the α-Mg, β-Mg17Al12 and Al2Ce strengthening phase composition, crystal grain was refined after adding rare earth, generating rare earth magnesium compounds Al2Ce. So the number of strengthening phase in grain boundary and form can play bigger role for mechanical properties of alloys. Because of the dispersion distribution, high melting point the heat stable partic les Al2Ce in existence, it play a nail pierced role of crystal grain, thus compare no adding rare earth alloy, adding rare earth alloy has better the mechanical performance.

Keywords: EMS Process; RE magnesium alloy; mechanical properties

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