The microstructure of dislocated martensitic steel: Theory
The microstructure of dislocated martensitic steel: Theory
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DOI：
10.1016/j.actamat.2014.04.038
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发表时间：
2014-09
期刊：
影响因子：
9.4
通讯作者：
L. Qi;A. Khachaturyan;J. Morris
中科院分区：
文献类型：
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作者：
L. Qi;A. Khachaturyan;J. Morris
最近对低碳钢中位错马氏体显微组织的实验研究表明，其表面上复杂的显微组织实际上是一种简单的分层模式，其基本元素是包含两个共享同一贝恩轴的α′相Kurdjumov-Sachs变体的复合块。这些块是具有通常平行于 {0 1 1}α 平面的界面的板，可以堆叠成四个晶体学上可区分的包。当原奥氏体晶粒包含所有四个组时，其转变可以是不涉及净剪切的简单膨胀。在本文中，我们利用位错马氏体的晶体学理论表明，堆叠式复合马氏体板是可以构造的最简单的相变板，它保留了密排平面 ({0 1 1}α||{1 1 1}γ) 并具有不变的 {1 1 1}γ 习性面，正如实验结果所要求的那样。该板的 12 种不同变体可以配置成微观结构，复制实验中发现的图案和极图。结果表明，没有单变体马氏体板可以以这种方式堆叠而不会产生很大的应变，尽管该理论确实预测了具有 {5 5 7}αhabit 平面和 Greninger-Troiano 取向关系的单变体板，这些在含有大量残余奥氏体的合金中发现。
Recent experimental studies of the microstructure of dislocated martensite in low-carbon steel have shown that its superficially complex microstructure is, in fact, a simple hierarchical pattern whose basic element is a composite block containing two Kurdjumov–Sachs variants of the α′ phase that share the same Bain axis. The blocks are plates with interfaces generally parallel to {0 1 1}αplanes that can be stacked into four crystallographically distinguishable packets. When the prior austenite grain contains all four packets its transformation can be a simple dilatation that involves no net shear. In the present paper we use the crystallographic theory of dislocated martensite to show that the stackable composite martensite plate is the simplest transformed plate that can be constructed that preserves a close-packed plane ({0 1 1}α||{1 1 1}γ) and has an invariant {1 1 1}γhabit plane, as the experimental results require. The 12 distinct variants of this plate can be configured into a microstructure that duplicates the patterns and pole figures found experimentally. The results suggest that there is no single-variant martensite plate that can be stacked in this way without substantial strain, though the theory does predict the single-variant plates with {5 5 7}αhabit planes and Greninger–Troiano orientation relations that are found in alloys with large fractions of retained austenite.