马氏体相变唯象“理论”的评述—五评马氏体相变的切变学说

The Commentary onPhenomenological Theory of Martensite Phase Transformation—The Fifth Commentary on Shear Theory

摘要: 研究马氏体相变晶体学具有重要理论意义。本文简述并评价了唯象学说，指出：1) 以贝茵应变使母相转变为马氏体，缺乏热力学可能性，贝茵应变B作为计算数据，不可靠； 2) 马氏体浮凸是相变体积变化所致，与切变无关，浮凸普遍为帐篷型(∧)，矩阵计算式中的形状应变F与马氏体相变晶体学没有直接的联系；3) 点阵不变切变缺乏热力学可能性，在实际的马氏体相变中不存在简单切变(S)。同样，刚性转动也是虚构的；4) 唯象学说与马氏体相变实际不符，应予摈弃。

Abstract: It is of theoretical significance to study the crystallography of martensite phase transformation. The phenomenological theory was briefly described and evaluated. The proposed viewpoints are as follows. 1) The transformation from austenite to martensite through the Bain strain lacks of the thermodynamics possibility. Moreover, it is unreliable to use the Bain strain (B) as the calculating data; 2) The surface relief of martensite, which is generally in tent (∧) type, results from the bulk expansion during martensite phase transformation and has nothing to do with the shear. The shape strain (F) in the matrix calculation formula is not directly relevant to the crystallography of martensite phase transformation; 3) The lattice invariance shear is short of the thermodynamic feasibility. No simple shear (S) exists in the actual martensite phase transformation, similarly, the rigid rotation is imaginary; 4) The phenomenological theory doesn’t conform to the reality of martensite phase transformation and should be abandoned.

1. 引言

20世纪50年代前期由M. S. Wechsler等(w-L-R)[1] 和J. S. Bowles等(B-N)[2] 分别独立地提出了马氏体相变晶体学的唯象“理论”：W-L-R学说和B-M学说。这两个学说基本上等价，即两者的出发点和推理过程相近，该学说被认为是材料科学中为数不多的定量学说。由于唯象学说，或称表象学学说，与实际不符，理论上也欠妥当，故不能称为理论，称其为学说(或假说)较为贴切。该学说经过多年的修改仍不成熟，与实际相差甚远[3] -[5] 。本文从试验和理论上对该学说进行了分析并指出其误区。

2. 表象学“理论”要点简述