Sn纳米颗粒增强镁基复合材料的组织性能研究

发布时间：2018-01-29 01:06

本文关键词： Sn纳米颗粒 AZ31镁合金显微组织力学性能　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：颗粒增强镁基复合材料具有力学性能呈各向同性、制备工艺简单、易机械加工等特点,是目前最有可能实现低成本、规模化生产的镁基复合材料。近年来,通过引入微、纳米级粒子制备颗粒增强镁基复合材料,提高镁合金强度、塑性方面做了许多成功的尝试,这将会拓宽镁合金在电子、通信、现代汽车、航空航天等领域的应用。本文选用AZ31镁合金为基体,直流电弧等离子体法制备Sn纳米颗粒并作为引入颗粒,采用搅拌铸造法制备Mg2Sn/AZ31镁基复合材料,并与Sn锭形式引入作对比。利用X射线衍射仪、光学显微镜、扫描电子显微镜以及室温拉伸试验仪等多种分析测试方法,研究Sn纳米颗粒的引入对AZ31镁合金组织性能的影响。主要结论如下：(1)直流电弧等离子体法制备的Sn纳米颗粒,粒径均匀,大小在40-80nm之间,颗粒形态为球形,表面有一层厚度约6nm的氧化物包覆。(2)无论Sn以何种形式引入,均可与Mg原位反应生成Mg2Sn增强相。引入Sn纳米颗粒时,可在基体中形成纳米级Mg2Sn颗粒,但主要以团簇形式存在；Sn锭的引入则在基体中形成微米级的粗大Mg2Sn颗粒。(3)引入1wt.%Sn纳米颗粒时,β-Mg17Al12相主要以骨骼状断续地分布在α-Mg的晶界处；由于Mg2Sn相与β-Mg17Al12相的分布存在重叠性,当进一步增加Sn纳米颗粒的含量(3wt.%),Mg2Sn纳米颗粒之间团聚加重,以“链状”分布于晶界处,使得骨骼状β-Mg17Al12又会连续地分布。(4)Sn纳米颗粒的引入,使AZ31镁合金的性能得到一定的提高,引入量为1wt.%时,抗拉强度、伸长率分别提高35.6%、83.6%,但略低于引入1wt.%Sn锭时材料的性能,这与Sn纳米颗粒在熔炼过程中的烧损导致其实际引入量较少以及纳米级Mg2Sn颗粒以团簇形式存在有关。
[Abstract]:Particle reinforced magnesium matrix composites have the characteristics of isotropic mechanical properties, simple preparation process, easy machining, and are the most likely to achieve low-cost, large-scale production of magnesium matrix composites in recent years. Through the introduction of microparticles, nano-particles to prepare particulate reinforced magnesium matrix composites, improve the strength of magnesium alloys, plastic aspects of a lot of successful attempts, which will broaden the magnesium alloy in electronics, communications, modern cars. In this paper, Sn nanoparticles were prepared by DC arc plasma method with AZ31 magnesium alloy as the substrate. Mg2Sn/AZ31 magnesium matrix composites were prepared by agitation casting and compared with Sn ingot. X-ray diffractometer and optical microscope were used. Scanning electron microscope (SEM) and room temperature tensile tester are used in this paper. The effect of Sn nanoparticles on the microstructure and properties of AZ31 magnesium alloy was studied. The main conclusions are as follows: 1) the size of Sn nanoparticles prepared by DC arc plasma method is uniform. The size is 40-80 nm, the particle shape is spherical, and the surface is covered with an oxide coating of about 6 nm.) no matter what form Sn is introduced. When Sn nanoparticles were introduced, nano-sized Mg2Sn particles could be formed in the matrix, but mainly in the form of clusters. On the other hand, the introduction of Sn ingot forms a coarse Mg2Sn particle of micron size in the matrix. 尾 -Mg17Al12 phase mainly distributes intermittently in the grain boundary of 伪 -Mg. Because the distribution of Mg2Sn phase and 尾 -Mg17Al12 phase is overlapped, the agglomeration between Mg2Sn nanoparticles is aggravated when the content of Sn nanoparticles is further increased. The "chain" distribution at grain boundaries makes the introduction of skeleton 尾 -Mg17Al12 and the introduction of nanocrystalline Sn particles can improve the properties of AZ31 magnesium alloys to a certain extent. The tensile strength and elongation increased 35.63.6when the amount of 1wt.% was introduced, but it was slightly lower than that of 1wt.Sn ingot. This is related to the small amount of Sn nanoparticles in the melting process and the existence of nanocrystalline Mg2Sn particles in the form of clusters.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333

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