Mechanical properties of Fe rich Fe-Si alloys: Ab initio local bulk-modulus viewpoint

Somesh Kr Bhattacharya, Masanori Kohyama, Shingo Tanaka, Yoshinori Shiihara, Arkapol Saengdeejing, Ying Chen, Tetsuo Mohri

研究成果: Article査読

6 被引用数 (Scopus)

抄録

Fe-rich Fe-Si alloys show peculiar bulk-modulus changes depending on the Si concentration in the range of 0-15 at.%Si. In order to clarify the origin of this phenomenon, we have performed density-functional theory calculations of supercells of Fe-Si alloy models with various Si concentrations. We have applied our recent techniques of ab initio local energy and local stress, by which we can obtain a local bulk modulus of each atom or atomic group as a local constituent of the cell-averaged bulk modulus. A2-phase alloy models are constructed by introducing Si substitution into bcc Fe as uniformly as possible so as to prevent mutual neighboring, while higher Si concentrations over 6.25 at.%Si lead to contacts between SiFe8 cubic clusters via sharing corner Fe atoms. For 12.5 at.%Si, in addition to an A2 model, we deal with partial D03 models containing local D03-like layers consisting of edge-shared SiFe8 cubic clusters. For the cell-averaged bulk modulus, we have successfully reproduced the Si-concentration dependence as a monotonic decrease until 11.11 at.%Si and a recovery at 12.5 at.%Si. The analysis of local bulk moduli of SiFe8 cubic clusters and Fe regions is effective to understand the variations of the cell-averaged bulk modulus. The local bulk moduli of Fe regions become lower for increasing Si concentration, due to the suppression of bulk-like d-d bonding states in narrow Fe regions. For higher Si concentrations till 11.11 at.%Si, corner-shared contacts or 1D chains of SiFe8 clusters lead to remarkable reduction of local bulk moduli of the clusters. At 12 at.%Si, on the other hand, two- or three-dimensional arrangements of corner- or edge-shared SiFe8 cubic clusters show greatly enhanced local bulk moduli, due to quite different bonding nature with much stronger p-d hybridization. The relation among the local bulk moduli, local electronic and magnetic structures, and local configurations such as connectivity of SiFe8 clusters and Fe-region sizes has been analyzed. The ab initio local stress has opened the way for obtaining accurate local elastic properties reflecting local valence-electron behaviors.

本文言語English
論文番号116518
ジャーナルMaterials Research Express
4
11
DOI
出版ステータスPublished - 2017 11

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 生体材料
  • 表面、皮膜および薄膜
  • ポリマーおよびプラスチック
  • 金属および合金

フィンガープリント

「Mechanical properties of Fe rich Fe-Si alloys: Ab initio local bulk-modulus viewpoint」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル