马氏体相变的晶体学特征—不变平面应变

自20世纪20年代以来,基于马氏体相变产生的浮凸和在母相中预先刻制的直线变成在相界面上连续的折线,提出了以切变为基础的马氏体相变的晶体学特征—"不变平面应变"的概念。随后,以该概念为基础建立了马氏体相变晶体学表象理论(PTMC)。然而,刘宗昌等基于相同的实验,即马氏体相变后的直线刻痕仍为直线和浮凸形态为帐篷形,分别在2010年和2013年《热处理》杂志上发表文章,否定马氏体相变的"切变"机制进而否定马氏体相变的"不变平面应变"。如所周知,否定马氏体相变的"切变机制"就是否定"不变平面应变",因此刘宗昌等于2013年发表的文章彰显出他们的轻率。本文作者已在3篇文章中列举用原子力显微镜和透射电镜观察的结果驳斥了他们的错误观点,至少可以说,他们没有理解我们文章中的实验和理论。为此,本文再次引用Yang和Wayman的透射电镜实验结果,即单变体马氏体使预存在的层错迹线(直线)变成折线,而自协调的多个马氏体可使迹线仍为直线;单变体马氏体的浮凸为N形,但多变体马氏体的浮凸可以是帐篷形或更为复杂的形态,由此可以说明刘宗昌等错误观点的原因。最近,本文作者及其合作者基于PTMC计算了Mn80Fe15Cu5热弹性合金马氏体相变的惯习面,并与实验结果相符,由此确认了"不变平面应变"是马氏体相变晶体学特征的正确性。

The Crystallography Characteristics of Martensitic Transformation-Invariable Plane Strain

Since 1920’ s, based on the fact that both the surface relief produced by martensitic transformation and a previously marked straight-line scratch changing into a continuous fold line at martensite-austenite interface , the concept of invariable plane strain as the crystallography characteristic of martensitic transformation on the basis of the shear was proposed .Subsequently , the phenomenological theory of martensite crystallography （ PTMC ） was built on the basis of the invariable plane strain .In 2010 and 2013 in《Heat Treatment》,however , LIU Zongchang et al published papers where they denied the shear mechanism and further denied the invariable plane strain for martensitic transformation according to their experimental results that a straight-line scratch do not change and the relief exhibits tent-shaped after the martensitic transformation .It is well known that to deny the shear mechanism of＆amp;nbsp;martensitic transformation is to deny the invariable plane strain and , therefore , LIU et al publishing paper in 2013 is from haste . Author of this paper criticized their wrong viewpoints by results obtained from atomic force microscopy and transmission electron microscopy observations in three published papers .It is at least said that LIU et al do not understand experiments and the related theories in three papers mentioned above . Therefore , experimental results of Yang and Wayman , that is, the trace of stacking fault （straight line） will change into the fold line when it is shorn by a single martensitic variant , but still is a straight line when it is shorn by multiple martensitic variants with self-accommodation , and the surface relief may exhibit N -shaped for a single martensitic variant and tent-shaped or more complex shape for two or more martensitic variants , were cited again in this paper , which may reveal the origin of LIU et als ’ wrong viewpoint .Recently , the habit plane of martensitic transformation in a Mn80Fe15Cu5 thermoelastic alloy is calculated by author and co-authors of this paper based on PTMC , and the calculated result was well consistent with the experimental result , which may confirm that the invariable plane strain is crystallography characteristic of martensitic transformation .