Si segregation at Fe grain boundaries analyzed by<i>ab initio</i>local energy and local stress

Bhattacharya, Somesh Kr.; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori

doi:10.1088/0953-8984/26/35/355005

Cited by 39 publications

(42 citation statements)

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“…All these results should be concerned with the covalent nature of Si-Fe bonds due to strong sp-d hybridization, which also induces a reduction in the magnetic moments of contacting Fe atoms as shown clearly in ref. 36. For GBs with much higher local Si concentrations, we do not deny the possibility of remarkable changes in the elastic and mechanical properties of GB regions observed in Fe-Si alloys, but this should be investigated in the future.…”

Section: C) E S Is In Units Of Ev/si Atommentioning

confidence: 81%

“…40 The reduction in the adhesion energies of Si-segregated GBs compared to pure Fe GBs is rather small as examined in ref. 36. It seems that Si-Fe bonds enhance local Young's moduli and suppress the interface weakening in the segregation at a tighter site as shown in Fig.…”

Section: C) E S Is In Units Of Ev/si Atommentioning

confidence: 85%

“…36 By applying our local-energy scheme, the segregation mechanism can be efficiently analyzed via the local-energy decomposition of the segregation energy. The segregation energy E S for a substitutional Si atom at a GB is defined as the totalenergy difference between the systems of a GB and a bulk crystal before and after the GB segregation.…”

Section: Local-energy and Local-stress Analyses Of Si Segregation At mentioning

confidence: 99%

“…7 Local-energy decomposition of the GB segregation energy of a substitutional impurity atom. 36 The segregation energy is defined by the total-energy change from the initial system (left two structures) consisting of a pure GB and a bulk crystal containing an isolated impurity to the final system (right two configurations) consisting of an impurity-segregated GB and a pure bulk crystal. By the local-energy decomposition, the segregation energy is expressed by a sum of the four terms, T 1 , T 2 , T 3 , and T 4 ) in the atomic sites of the Σ3 (111) GB in Fe.…”

Section: Local-energy and Local-stress Analyses Of Si Segregation At mentioning

confidence: 99%

“…8 Atomic Young's moduli in the pure and Si-segregated Σ11 (332) GBs in Fe. 36 Plots in red in both the figures are results of the Si substitution at "1a" and "1b", respectively, in contrast to those of the pure GB in black. The segregation sites "1a" and "1b" are shown in Fig.…”

Section: Dislocationmentioning

confidence: 99%

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Mechanical properties of Fe-rich Si alloy from Hamiltonian

et al. 2017

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The physical origins of the mechanical properties of Fe-rich Si alloys are investigated by combining electronic structure calculations with statistical mechanics means such as the cluster variation method, molecular dynamics simulation, etc, applied to homogeneous and heterogeneous systems. Firstly, we examined the elastic properties based on electronic structure calculations in a homogeneous system and attributed the physical origin of the loss of ductility with increasing Si content to the combined effects of magneto-volume and D0 3 ordering. As a typical example of a heterogeneity forming a microstructure, we focus on grain boundaries, and segregation behavior of Si atoms is studied through high-precision electronic structure calculations. Two kinds of segregation sites are identified: looser and tighter sites. Depending on the site, different segregation mechanisms are revealed. Finally, the dislocation behavior in the Fe-Si alloy is investigated mainly by molecular dynamics simulations combined with electronic structure calculations. The solid-solution hardening and softening are interpreted in terms of two kinds of energy barriers for kink nucleation and migration on a screw dislocation line. Furthermore, the clue to the peculiar work hardening behavior is discussed based on kinetic Monte Carlo simulations by focusing on the preferential selection of slip planes triggered by kink nucleation.npj Computational Materials (2017) 3:10 ; doi:10.1038/s41524-017-0012-4 INTRODUCTION Mechanical properties of alloys originate from the behavior of electrons and atoms on the microscopic scale; however, the strength of atomic bonding does not directly relate to macroscopic mechanical properties such as the yield strength, fracture toughness, and fatigue resistance. This is because the microstructure on the mesoscale, which is composed of various defects such as impurities, grain boundaries, and dislocations, mediates or enhances the response of alloys against external forces, leading to fairly nonlinear and multiscale phenomena. Facing such a nonlinear nature associated with the strength and plastic deformation of alloys, identifying the controlling factors for the mechanical properties is a significantly difficult task, and clarifying the underlying physics at different length and time scales still remains a major challenge in materials science.The authors of the present article took up the challenge of this complicated problem with their particular theoretical and computational tools unique to each characteristic scale range. These tools are electronic structure calculations, the cluster variation method (CVM) of statistical mechanics, and molecular dynamics (MD) simulations, which may cover the atomic to mesoscopic scale ranges. By virtue of high-performance computers, some of the results obtained by the present calculations achieve a higher precision and reveal a clearer picture than those obtained by ordinary experiments.Among the various mechanical properties, the main focus of the present study is the solid-solut...

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Section: C) E S Is In Units Of Ev/si Atommentioning

confidence: 81%

Section: C) E S Is In Units Of Ev/si Atommentioning

confidence: 85%

Section: Local-energy and Local-stress Analyses Of Si Segregation At mentioning

confidence: 99%

Section: Local-energy and Local-stress Analyses Of Si Segregation At mentioning

confidence: 99%

Section: Dislocationmentioning

confidence: 99%

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