Structural and Elastic Properties of Fe-Ge Alloys: ab initio studies

Михаил Александрович Загребин, Мария Викторовна Матюнина, Владимир Владимирович Соколовский, Василий Дмитриевич Бучельников


In this paper, with the help of the density functional theory, the structural and elastic properties of A2, B2, D03, and L12 phases of Fe100–xGex alloys (12,5 ≤ x ≤ 28,125 at. %) have been studied. The electronic and full ionic relaxations were used for the investigation of crystal structures. The concentration dependencies of the atomic volumes, structural phase transition temperatures, tetragonal and rhombohedral shear moduli have been calculated. We show that the atomic volume curves correlate with the sequence of phase transitions observed experimentally: A2→B2→D03 (x ≤ 22 at. % of Ge content). The structural phase transition temperatures increase with the Ge concentration. The calculated tetragonal moduli for the D03, A2, and L12 structures decrease with the increasing of the Ge content, what agrees with the experimental results. The dependence of rhombohedral shear moduli as a function of Ge concentration does not change significantly with increasing Ge atoms. The C44 is increased for the D03 phase, while for A2, B2, and L12, it decreases.

Ключевые слова

ab initio; crystal structure; phase transformations; elastic moduli

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