摘要 众所周知，材料的机械性能与微观组织之间有着密切关系，因此研究材料的微观组织演化对于理解和预测材料性能具有重大意义。 局限于实验手段的有限性，近几十年来计算机模拟技术在研究材料微观组织方面得到了飞速发展。其中相场法作为一种模拟晶粒长大和微观组织演化的介观模型因其简单的计算过程和直观的模拟结果而受到推崇。
本课题基于板条马氏体相变晶体学模型提出了一种简单有效的双切变模型。该模型主要思想是通过在板条马氏体内部引入位错滑移机制，来实现马氏体相转变，从而形成板条马氏体的微观组织结构。本课题正是基于这一物理模型，引入相场法，建立弹塑性相场模型，模拟板条马氏体晶粒长大过程，通过计算相变过程的平均塑性应变来估算板条马氏体内部可能存在的最大位错密度，并与实验结果相比较, 发现通过模拟得到的计算结果与实验结果符合良好。19198
毕业论文关键词：板条马氏体，相场法，位错密度
Title The estimation of the maximum dislocation density in lath martensite by phase-field method
Abstract
As known to us, the mechanical properties of materials are closely related to the
microstructure evolution, which is of great significance on the understanding and
prediction of the properties in materials. Confined to the limited experimental methods,
the computer simulation developed in recent decades has a big progress. Phase field
method as a meso scale model is widely used to simulate the grain growth and
microstructural evolution because of its simple calculation procedures and intuitive
simulation results.
In this study, we proposed a simple and effective two types of slip deformation (TTSD)
model based on the phenomenonlogical crystallographic model. The main idea of the
model is to introduce dislocation slip to realize the martensitic transformation, resulting
in the hierarchical microstructure of lath martensite. Based on this physical model, we
introduced phase-field method and established an elasto-plastic phase-field model.
Then the martensitic transformation is simulated by the model. The maximum
dislocation density is calculated by the slip deformation strain, which is generated by
our model. And the simulation results are well consistent with the experimental results.
Keywords: lath martensite, phase field method, dislocation density
目次
1 绪论.. 2
1.1 引言 . 2
1.2 马氏体微观结构与相变晶体学 2
1.3 相场法 . 5
1.4 相场法研究板条马氏体的现状 7
1.5 现阶段研究的目的 . 7
2 板条马氏体的相变物理模型.. 8
2.1 介绍 . 8
2.2 双切变模型 . 8
3 相场法数值模拟 17
3.1 介绍 17
3.2 边界条件设定 17
3.3 模拟结果与讨论 .. 18
4 利用相场法估算板条马氏体中最大位错密度.. 20
4.1 介绍 20
4.2 计算方法 . 20
4.3 结果与讨论 23
4.4 实验数据比对 . 26
结论 27
致谢 28
参考文献.. 29
1 绪论
1.1 引言
板条马氏体由于其优越的力学性能而成为新型高强度钢的重要组成相。 实验
观测表明板条马氏体具有复杂的层状结构和高密度盘结纠缠的位错， 正因为如此
才导致了板条马氏体跟其它形态的马氏体相比具有较高强度。 由此可见研究板条 利用相场法估算板条马氏体内部最大位错密度:http://www.751com.cn/cailiao/lunwen_10471.html