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Derived crystal structure of martensitic materials by solid-solid phase transformation.
Acta Crystallographica Section A: Foundations and Advances ( IF 1.9 ) Pub Date : 2020-06-30 , DOI: 10.1107/s2053273320006087
Mostafa Karami 1 , Nobumichi Tamura 2 , Yong Yang 3 , Xian Chen 1
Affiliation  

A mathematical description of crystal structure is proposed consisting of two parts: the underlying translational periodicity and the distinct atomic positions up to the symmetry operations in the unit cell, consistent with the International Tables for Crystallography . By the Cauchy–Born hypothesis, such a description can be integrated with the theory of continuum mechanics to calculate a derived crystal structure produced by solid–solid phase transformation. In addition, the expressions for the orientation relationship between the parent lattice and the derived lattice are generalized. The derived structure rationalizes the lattice parameters and the general equivalent atomic positions that assist the indexing process of X‐ray diffraction analysis for low‐symmetry martensitic materials undergoing phase transformation. The analysis is demonstrated in a CuAlMn shape memory alloy. From its austenite phase (L21 face‐centered cubic structure), it is identified that the derived martensitic structure has orthorhombic symmetry Pmmn with the derived lattice parameters a d = 4.36491, b d = 5.40865 and c d = 4.2402 Å, by which the complicated X‐ray Laue diffraction pattern can be well indexed, and the orientation relationship can be verified.

中文翻译:

通过固-固相变获得马氏体材料的晶体结构。

提出了晶体结构的数学描述,它由两部分组成:基本的平移周期性和直至晶格中对称操作的不同原子位置,与《国际晶体学表》一致。通过柯西-伯恩假说,可以将这种描述与连续体力学理论相结合,以计算通过固-固相变产生的派生晶体结构。另外,归纳了母晶格和导出晶格之间的取向关系的表达式。派生的结构合理化了晶格参数和一般的等效原子位置,这有助于对经历相变的低对称马氏体材料进行X射线衍射分析的索引过程。该分析在CuAlMn形状记忆合金中得到证明。从其奥氏体相(L2 1面心立方结构)可以确定,派生的马氏体结构具有正交各向异性Pmmn通过推导的晶格参数a d = 4.36491,b d = 5.40865和c d = 4.2402Å,可以很好地索引复杂的X射线劳厄衍射图,并可以验证取向关系。
更新日期:2020-07-01
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