喷射沉积镁合金热压缩过程组织性能的研究

发布时间：2018-01-25 01:50

  本文关键词： 喷射沉积镁合金 (Ca Nd)Al2 热压缩 LPSO 织构　出处：《内蒙古科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：镁合金是工程应用中最轻的结构金属，具有比强度高以及减震性好等优势，，成为航空航天、汽车、军工等领域实现轻量化和节能减排的理想材料。与传统铸造镁合金相比，喷射沉积技术制备的镁合金晶粒细小、热稳定性高、合金化程度高、综合力学性能优良。但是镁合金为HCP结构，塑性成形能力差，在变形过程中容易形成强烈的(0002)基面织构，严重限制了其应用。 已有研究表明，稀土元素Nd和合金元素Ca的添加可以有效降低变形时基面织构的强度，关于在Ca/Nd复合添加高合金化条件下，喷射沉积镁合金热变形过程组织及织构演变规律研究目前较少。本文以喷射沉积镁合金挤压坯Mg-9Al-3Zn-6Ca-1Mn-1Nd为研究对象，在不同工艺条件下对其进行单道次热压缩变形，重点研究单道次热压缩变形过程中合金组织、织构的演变规律，以及变形工艺对合金热压缩微观组织及织构的影响。主要研究结果如下： （1）喷射沉积镁合金挤压坯晶粒尺寸在3μm左右，基体中分布着大量尺寸300nm左右的“含Nd的Al2Ca相”((Ca,Nd)Al2)。合金中的层片状组织为Mg-Nd-Zn系24R型LPSO结构，挤压坯中已经形成了很强的(0002)基面织构。 （2）在变形温度250℃、应变速率1s-1条件下，对喷射沉积镁合金挤压坯进行单道次热压缩变形，随变形程度(ε=0.1、0.3、0.6)的增加合金柱面和锥面织构逐渐增强、而基面织构强度显著降低，当变形程度为0.6时，合金内形成了基面、柱面和锥面共存的“复合织构”类型。 （3）不同温度(250℃、300℃、350℃)、应变速率(0.01s-1、0.1s-1、1s-1)条件下对挤压坯进行变形程度0.6的热压缩变形，随温度(250℃、300℃、350℃)的升高、应变速率(0.01s-1、0.1s-1、1s-1)的增加，合金织构的“随机化”程度增加，并且在变形温度350℃、应变速率1s-1的条件下合金形变织构的“随机化”程度达到最高。
[Abstract]:Magnesium alloy is the lightest structural metal in engineering application. It has the advantages of high specific strength and good shock absorption. Magnesium alloy has become aerospace and automobile. Compared with the traditional casting magnesium alloy, the magnesium alloy prepared by spray deposition technology has fine grain, high thermal stability and high alloying degree. The comprehensive mechanical properties of magnesium alloy are excellent, but magnesium alloy is of HCP structure, and its plastic forming ability is poor, so it is easy to form strong texture of base plane in the process of deformation, which seriously limits its application. It has been shown that the addition of rare earth element ND and alloy element Ca can effectively reduce the strength of basic surface texture during deformation. There are few studies on the microstructure and texture evolution of spray deposited magnesium alloy during hot deformation. In this paper, Mg-9Al-3Zn-6Ca-1Mn-1Nd of extruded magnesium alloy is taken as the research object. Single pass thermal compression deformation was carried out under different technological conditions, and the evolution of microstructure and texture during single pass hot compression deformation was studied. And the effect of deformation process on the microstructure and texture of the alloy under hot compression. The main results are as follows: 1) the grain size of extruded magnesium alloy is about 3 渭 m, and a large amount of Al2Ca phase containing ND is distributed in the matrix. The lamellar structure of the alloy is Mg-Nd-Zn 24R type LPSO structure, and a strong basic texture has been formed in the extruded billet. (2) under the condition of deformation temperature 250 鈩

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