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Title: Self-learning kinetic Monte Carlo simulations of diffusion in ferromagnetic α -Fe–Si alloys

Abstract

Diffusion in α-Fe-Si alloys is studied using AKSOME, an on-lattice self-learning KMC code, in the ferromagnetic state. Si diffusivity in the α-Fe matrix were obtained with and without the magnetic disorder in various temperature ranges. In addition we studied vacancy diffusivity in ferromagnetic α-Fe at various Si concentrations up to 12.5at.% in the temperature range of 350–550 K. The results were compared with available experimental and theoretical values in the literature. Local Si-atom dependent activation energies for vacancy hops were calculated using a broken-model and were stored in a database. The migration barrier and prefactors for Si-diffusivity were found to be in reasonable agreement with available modeling results in the literature. Magnetic disorder has a larger effect on the prefactor than on the migration barrier. Prefactor was approximately an order of magnitude and the migration barrier a tenth of an electron-volt higher with magnetic disorder when compared to a fully ferromagnetic ordered state. In addition, the correlation between various have a larger effect on the Si-diffusivity extracted in various temperature range than the magnetic disorder. In the case of vacancy diffusivity, the migration barrier more or less remained constant while the prefactor decreased with increasing Si concentration in the disorderedmore » or A2-phase of Fe-Si alloy. Important vacancy-Si/Fe atom exchange processes and their activation barriers were also identified and discuss the effect of energetics on the formation of ordered phases in Fe-Si alloys.« less

Authors:
ORCiD logo; ; ; ; ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1414534
Report Number(s):
PNNL-SA-124267
Journal ID: ISSN 0953-8984
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physics. Condensed Matter; Journal Volume: 30; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
Kinetic Monte Carlo; Vacancy Diffusion; Silicon Steels; AKSOME; Alloys

Citation Formats

Nandipati, Giridhar, Jiang, Xiujuan, Vemuri, Rama S., Mathaudhu, Suveen, and Rohatgi, Aashish. Self-learning kinetic Monte Carlo simulations of diffusion in ferromagnetic α -Fe–Si alloys. United States: N. p., 2017. Web. doi:10.1088/1361-648X/aa9774.
Nandipati, Giridhar, Jiang, Xiujuan, Vemuri, Rama S., Mathaudhu, Suveen, & Rohatgi, Aashish. Self-learning kinetic Monte Carlo simulations of diffusion in ferromagnetic α -Fe–Si alloys. United States. doi:10.1088/1361-648X/aa9774.
Nandipati, Giridhar, Jiang, Xiujuan, Vemuri, Rama S., Mathaudhu, Suveen, and Rohatgi, Aashish. Tue . "Self-learning kinetic Monte Carlo simulations of diffusion in ferromagnetic α -Fe–Si alloys". United States. doi:10.1088/1361-648X/aa9774.
@article{osti_1414534,
title = {Self-learning kinetic Monte Carlo simulations of diffusion in ferromagnetic α -Fe–Si alloys},
author = {Nandipati, Giridhar and Jiang, Xiujuan and Vemuri, Rama S. and Mathaudhu, Suveen and Rohatgi, Aashish},
abstractNote = {Diffusion in α-Fe-Si alloys is studied using AKSOME, an on-lattice self-learning KMC code, in the ferromagnetic state. Si diffusivity in the α-Fe matrix were obtained with and without the magnetic disorder in various temperature ranges. In addition we studied vacancy diffusivity in ferromagnetic α-Fe at various Si concentrations up to 12.5at.% in the temperature range of 350–550 K. The results were compared with available experimental and theoretical values in the literature. Local Si-atom dependent activation energies for vacancy hops were calculated using a broken-model and were stored in a database. The migration barrier and prefactors for Si-diffusivity were found to be in reasonable agreement with available modeling results in the literature. Magnetic disorder has a larger effect on the prefactor than on the migration barrier. Prefactor was approximately an order of magnitude and the migration barrier a tenth of an electron-volt higher with magnetic disorder when compared to a fully ferromagnetic ordered state. In addition, the correlation between various have a larger effect on the Si-diffusivity extracted in various temperature range than the magnetic disorder. In the case of vacancy diffusivity, the migration barrier more or less remained constant while the prefactor decreased with increasing Si concentration in the disordered or A2-phase of Fe-Si alloy. Important vacancy-Si/Fe atom exchange processes and their activation barriers were also identified and discuss the effect of energetics on the formation of ordered phases in Fe-Si alloys.},
doi = {10.1088/1361-648X/aa9774},
journal = {Journal of Physics. Condensed Matter},
number = 3,
volume = 30,
place = {United States},
year = {Tue Dec 19 00:00:00 EST 2017},
month = {Tue Dec 19 00:00:00 EST 2017}
}