相变孪晶弹性场与马氏体构型的自反馈机制
发布时间：2019-03-03 14:47
【摘要】：马氏体相变的研究已近百年,现已广泛的应用于工程领域。CuAlNi形状记忆合金的优秀性能就是基于热弹性马氏体中的微观组织,但其中相变孪晶的形成机理至今仍不很完善。马氏体相变理论研究的进展将推动马氏体的应用,因此对孪晶机制的深入研究十分重要。本文研究的基本思想如下：马氏体相变中由于原子晶格改变将产生本征应变,从而产生自适应弹性场,弹性场将反过来影响孪晶构型的生长。本文将以马氏体微观结构及自适应现象为研究背景,通过有限元方法计算不同构型下弹性应力和应变场,旨在探明由本征应变导致的弹性场与马氏体孪晶构型的关系。本文基于文献中Hane和Shield的数据构建了奥氏体-孪晶马氏体及楔形孪晶马氏体两类构型,并通过弱形式自行编写了Freefem++代码对两类构型中的弹性场进行了有限元分析。对于奥氏体-孪晶马氏体构型,针对固定边界、自由边界和弹性边界下构型的弹性应力场进行了分析,结果表明孪晶的形成对应变能有减小作用。同时,相界面处本征应变的分布方式对应力场的分布具有很大影响,分析表明以梯度方式变化的本征应变可有效减少体系的弹性能。而对于楔形矛尖状孪晶马氏体,针对相同构型下的不同体积分数的楔形孪晶构型的剪应力场进行分析,发现随着孪晶体积分数的增长,沿惯习面的最大剪应力会先增大后减小,这表明马氏体的生长在一定阶段后将因为自身产生的弹性场而被抑制。沿惯习面剪应力的分析还表明马氏体相变以沿惯习面扩张的方式进行。
[Abstract]:The study of martensitic transformation has been studied for nearly 100 years and has been widely used in engineering field. The excellent properties of CuAlNi shape memory alloy are based on the microstructure of thermoelastic martensite, but the formation mechanism of transformation twins is still not perfect. The development of martensitic transformation theory will promote the application of martensite, so it is very important to study the twinning mechanism in depth. The basic ideas studied in this paper are as follows: in martensitic transformation, due to the change of atomic lattice, the intrinsic strain will be generated, and thus an adaptive elastic field will be generated, which in turn will affect the growth of twin configurations. In this paper, based on the microstructure and self-adaptive phenomena of martensite, the elastic stress and strain fields under different configurations are calculated by finite element method in order to find out the relationship between the elastic field caused by intrinsic strain and the twin configuration of martensite. Based on the data of Hane and Shield, two configurations of austenite-twin martensite and wedge-shaped twin martensite have been constructed in this paper, and the elastic fields in the two configurations have been analyzed by using the Freefem code compiled by themselves in weak form. For the austenite-twin martensite configuration, the elastic stress field of the configuration at fixed boundary, free boundary and elastic boundary is analyzed. The results show that the formation of twin has a decreasing effect on the strain energy. At the same time, the distribution mode of the intrinsic strain at the interface has a great influence on the distribution of the stress field. The analysis shows that the intrinsic strain with gradient mode can effectively reduce the elastic energy of the system. For the wedge-shaped twin martensite, the shear stress field of the wedge-shaped twin configuration with different volume fraction under the same configuration is analyzed. It is found that the maximum shear stress along the habitual plane increases first and then decreases with the increase of the volume fraction of the twin. This indicates that the growth of martensite at a certain stage will be inhibited by its own elastic field. The analysis of shear stress along the customary plane also shows that the martensitic transformation takes place along the customary plane.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.6
本文编号：2433795
[Abstract]:The study of martensitic transformation has been studied for nearly 100 years and has been widely used in engineering field. The excellent properties of CuAlNi shape memory alloy are based on the microstructure of thermoelastic martensite, but the formation mechanism of transformation twins is still not perfect. The development of martensitic transformation theory will promote the application of martensite, so it is very important to study the twinning mechanism in depth. The basic ideas studied in this paper are as follows: in martensitic transformation, due to the change of atomic lattice, the intrinsic strain will be generated, and thus an adaptive elastic field will be generated, which in turn will affect the growth of twin configurations. In this paper, based on the microstructure and self-adaptive phenomena of martensite, the elastic stress and strain fields under different configurations are calculated by finite element method in order to find out the relationship between the elastic field caused by intrinsic strain and the twin configuration of martensite. Based on the data of Hane and Shield, two configurations of austenite-twin martensite and wedge-shaped twin martensite have been constructed in this paper, and the elastic fields in the two configurations have been analyzed by using the Freefem code compiled by themselves in weak form. For the austenite-twin martensite configuration, the elastic stress field of the configuration at fixed boundary, free boundary and elastic boundary is analyzed. The results show that the formation of twin has a decreasing effect on the strain energy. At the same time, the distribution mode of the intrinsic strain at the interface has a great influence on the distribution of the stress field. The analysis shows that the intrinsic strain with gradient mode can effectively reduce the elastic energy of the system. For the wedge-shaped twin martensite, the shear stress field of the wedge-shaped twin configuration with different volume fraction under the same configuration is analyzed. It is found that the maximum shear stress along the habitual plane increases first and then decreases with the increase of the volume fraction of the twin. This indicates that the growth of martensite at a certain stage will be inhibited by its own elastic field. The analysis of shear stress along the customary plane also shows that the martensitic transformation takes place along the customary plane.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.6
【参考文献】
相关期刊论文 前9条
1 Xin Zhang;Qing-Suo Liu;;Influence of Alloying Element Addition on Cu Al Ni High-Temperature Shape Memory Alloy without Second Phase Formation[J];Acta Metallurgica Sinica(English Letters);2016年09期
2 胡义祥;丛海旭;;马氏体相变动力学及其图像模拟[J];理化检验(物理分册);2014年05期
3 计云萍;刘宗昌;任慧平;;钢中马氏体的孪晶亚结构[J];材料热处理学报;2013年04期
4 刘宗昌;计云萍;段宝玉;任慧平;;板条状马氏体的亚结构及形成机制[J];材料热处理学报;2011年03期
5 满蛟;张骥华;戎咏华;;马氏体相变中应变自协调效应的三维相场研究[J];金属学报;2010年07期
6 霍永忠;热弹性马氏体相变连续介质热力学研究[J];力学进展;2005年03期
7 徐祖耀;马氏体相变[J];热处理;1999年02期
8 徐祖耀;马氏体相变的分类[J];金属学报;1997年01期
9 徐祖耀;;马氏体相变研究的进展和瞻望[J];金属学报;1991年03期
相关博士学位论文 前1条
1 刘晓鹏;TiNi形状记忆合金薄膜显微结构及相变行为研究[D];大连理工大学;2002年
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