Systematization of the vast number of known crystal structures of intermetallic phases is a challenge. One previously proposed group is referred to here as vacancy variants of the W-type structure. Members of this group, may, however, not be easily recognized because of the structural irregularity introduced by the vacancies. Descriptions of the experimentally observed crystal structures of Ni3Sn4 and FeAl2 in terms of vacancy variants of the W-type structure are, respectively, derived by establishing a lattice correspondence with the W-type structure, allowing, in particular, identification of the vacant sites. In both cases only small deviatoric strains are required to obtain the experimentally encountered lattice parameters, and generally small atomic displacements occur from the ideal positions, thus demonstrating significance of the lattice correspondence. The lattice correspondences allow, for both Ni3Sn4 and FeAl2, relating reported microstructure evidence (directions/planes occurring in orientation relationships and crystal habits but also on twinning and slip) with such typical for metals and solid solutions with W-type (“bcc”) structures. This demonstrates that the established lattice correspondences have a significance going beyond a descriptive one, but the underlying W-type structures reveal themselves in the materials’ behavior.

中文翻译：

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Ni3Sn4 和 FeAl2 作为 W 型（“bcc”）结构的空位变体

大量已知金属间相晶体结构的系统化是一个挑战。先前提出的一组在此被称为W型结构的空位变体。然而，由于职位空缺造成的结构不规则，该群体的成员可能不容易被认出。实验观察到的 Ni 晶体结构的描述3锡4和铁铝2就W型结构的空位变体而言，分别通过与W型结构建立点阵对应来导出，特别是允许识别空位。在这两种情况下，只需要小的偏应变即可获得实验中遇到的晶格参数，并且通常会从理想位置发生小的原子位移，从而证明了晶格对应的重要性。晶格对应允许，对于 Ni3锡4和铁铝2，将报告的微观结构证据（取向关系和晶体习性中出现的方向/平面，以及孪生和滑移中出现的方向/平面）与具有 W 型（“bcc”）结构的金属和固溶体的典型情况相关联。这表明所建立的晶格对应关系的意义超出了描述性意义，但底层的 W 型结构在材料的行为中揭示了自身。