Strain-field effects on the formation and migration energies of self interstitials in alpha-Fe from first principles

Journal Article · Mon Mar 01 04:00:00 EST 2010 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.81.094102· OSTI ID:21366708

Zhengzheng, Chen; Kioussis, Nicholas ^[1]; Ghoniem, Nasr; Seif, Dariush ^[2]

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1. Department of Physics, California State University, Northridge, California 91330-8268 (United States)
2. Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095-1597 (United States)

Ab initio electronic structure calculations are employed to study the stability and mobility of mono-self interstitial atoms (SIA) in alpha-Fe under external deformation. The ab initio results indicate that the volumetric and uniaxial strain dependences of the SIA formation energy are different in the expansion and compression regimes, in contrast to the linear behavior in continuum elasticity theory. We find a <111>-><100> SIA reorientation mechanism induced by uniaxial expansion which proceeds via <11x>|{sub x=2.7} configuration. Volumetric and uniaxial deformations are also found to have a considerable influence on the migration paths and activation energy barriers for the <110>(110)reversible<100>(100) transformation and the <111>reversible<100> reorientation. The results reveal that (i) the volumetric expansion (compression) decreases (increases) substantially the migration energy barrier and renders the diffusion process three (one) dimensional, (ii) the uniaxial strain removes (decreases) the migration energy barrier for the <111>-><11x>|{sub x=2.7}(<11x>|{sub x=2.7}-><100>) transformation, leading to spontaneous reorientation of the <111> SIA, and (iii) the uniaxial deformation breaks the cubic symmetry of the system and in turn induces anisotropy of the migration rates along different directions. These calculations demonstrate that changes in the electronic structure induced by global elastic deformation lead to additional contributions to the formation and migration energies, which cannot be adequately accounted for neither by elasticity theory nor by empirical interatomic potentials.

• OSTI ID: 21366708
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 9 Vol. 81; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACTIVATION ENERGY
ANISOTROPY
COMPRESSION
COMPUTERIZED SIMULATION
CONFIGURATION
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DIFFUSION
ELASTICITY
ELECTRONIC STRUCTURE
ELEMENTS
ENERGY
ENTHALPY
EXPANSION
FORMATION HEAT
INTERSTITIALS
IRON
IRON-ALPHA
MECHANICAL PROPERTIES
METALS
MIGRATION
ONE-DIMENSIONAL CALCULATIONS
PHYSICAL PROPERTIES
POINT DEFECTS
REACTION HEAT
SIMULATION
STABILITY
STRAINS
SYMMETRY
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS