摘 要

本文借助MTS-810万能材料试验机和原子力显微镜对所制备出的柱状晶Cu-Al-Mn形状记忆合金进行循环加载拉伸实验并将拉伸后的样品与原样品放在原子力显微镜下观察拉伸前后样品的表面浮突，将两种样品表面浮突高度进行了比较，所得结果对于研究柱状晶Cu-Al-Mn形状记忆合金的马氏体相变宏观应变具有重要的指导意义。

论文主要研究了采用定向凝固技术制备出较好的柱状晶Cu-Al-Mn形状记忆合金，并用金相显微镜对合金的组织结构进行观察。 通过对Cu-Al-Mn形状记忆合金进行的循环拉伸实验，测得该组织合金的超弹性应变比普通多晶组织合金的3%提高到10.1%以上，并且，卸载后组织合金的残余应变小于0.3%。同时，对组织合金进行原位拉伸实验，观察其拉伸过程中表面析出的马氏体变体。将拉伸实验中的合金切割成合适尺寸，与未拉伸的合金样品分别放在原子力显微镜观察样表面浮凸形貌、并对高度定量分析。

研究结果表明：定向凝固的方法能制备出较好的柱状晶组织Cu-Al-Mn形状记忆合金，在室温下具有超过10%的超弹性。当合金在超弹性应变过程中，会发生马氏体的转变。采用原子力显微分析，拉伸前试样的表面浮突比循环拉伸40%卸载后的试样的表面浮突波动性更大，晶界表面的浮突会有明显的凸起，且高于小范围区域内的表面浮突。

本文的特色：采用了偏光实验来观察柱状晶Cu-Al-Mn形状记忆合金做原位拉伸实验中的每一阶段的合金生出的马氏体，这样我们可以很清晰的将拉伸实验的过程中生出的马氏体样貌显示出来。

关键词：Cu-Al-Mn形状记忆合金；超弹性；马氏体；表面浮突；柱状晶组织

Abstract

In this paper, the prepared columnar Cu-Al-Mn shape memory alloy was subjected to cyclic loading and tensile test by means of MTS-810 universal material testing machine and atomic force microscope. The tensile samples were placed on an atomic force microscope The results show that it is important to study the macroscopic strain of martensitic transformation of Cu-Al-Mn shape memory alloy in columnar crystals.

In this paper, the columnar Cu-Al-Mn shape memory alloy was prepared by directional solidification technique, and the microstructure of the alloy was observed by metallographic microscope. The superelastic strain of the microstructure alloy was improved by more than 10% of the ordinary polycrystalline alloy by the cyclic tensile test of Cu-Al-Mn shape memory alloy, and the residual strain of the alloy after unloading Less than 0.3%. At the same time, the in-situ tensile test was carried out on the microstructure of the alloy, and the martensitic variants were observed during the stretching process. The alloy in the tensile test was cut into the appropriate size, and the unstretched alloy samples were placed on an atomic force microscope to observe the surface embossed morphology, and the high quantitative analysis.

The results show that the Cu - Al - Mn shape memory alloy with better columnar structure can be prepared by directional solidification, and it has more than 10% superelasticity at room temperature. When the alloy in the process of superelastic strain, martensite transformation occurs. Using the atomic force microscopy, the surface flap of the sample before stretching is 40% higher than that of the sample. The surface floating velocity of the specimen is larger, and the floating surface of the grain boundary surface will be obviously raised and high Surface flaws in small areas.

The characteristics of this paper: polarized experiments were used to observe the columnar Cu-Al-Mn shape memory alloy in situ tensile test at each stage of the alloy of martensite, so that we can very clearly the tensile test The process of martensite appearance is displayed.

Key words: Cu-Al-Mn shape memory alloy; superelasticity; martensite; surface floatation; columnar crystal structure

目录

第1章 绪论 1

1.1 Cu-Al-Mn形状记忆合金概述 1

1.1.1 形状记忆合金及其特性 1

1.1.2 Cu基形状记忆合金的应用 1

1.1.3 Cu基形状记忆合金的发展前景 3

1.2柱状晶Cu-Al-Mn形状记忆合金的马氏体相变宏观应变特征研究的现状 3

1.2.1马氏体的定义 4

1.2.2马氏体相变的定义 4

1.2.3表面浮突的定义 5

1.3 课题背景及研究意义

1.3.1 课题背景 5

1.3.2 研究意义 6

第2章 研究内容和技术路线 7

2.1研究内容 7

2.2技术路线 7

第3章 柱状晶Cu-Al-Mn形状记忆合金的制备和组织分析 9

3.1柱状晶Cu-Al-Mn形状记忆合金的制备 9

3.2柱状晶Cu-Al-Mn形状记忆合金组织分析 10

3.2.1实验方法 10

3.2.2柱状晶Cu-Al-Mn形状记忆合金微观组织 11

第4章 柱状晶Cu-Al-Mn形状记忆合金的原位拉伸相变研究 12

4.1实验材料和实验方法 12

4.2板状拉件的超弹性循环加载实验 12

4.3柱状晶Cu-Al-Mn形状记忆合金的超弹性性能 14

第5章 柱状晶Cu-Al-Mn形状记忆合金的表面浮突实验研究 20

5.1实验材料和试验方法 20

5.1.1实验材料 20

5.1.2 试验方法 20

5.2 表面浮突实验研究分析 21

结 论 26

参考文献 27

致 谢 29

第1章 绪论

1.1 Cu-Al-Mn形状记忆合金概述

1.1.1 形状记忆合金及其特性

某些具有热弹性或应力诱发马氏体相变的材料，处在马氏体状态时，当进行一定限度的变形后，加热至超过马氏体相消失温度时,材料又能完全恢复至变形前的形状和体积，这种功能（如图1-1所示）叫作形状记忆特性（Shape Memory Effect，简称SME），在应力从零逐渐增大的过程中，记忆合金会先从弹性阶段加载到超弹性阶段，当卸载应力时，记忆合金会基本恢复到初始的状态，我们将具有形状记忆效应的合金称为形状记忆合金（Shape Memory Alloy，简称SMA）。

图1-1形状记忆效应示意图