Evolution of Symmetrical Grain Boundaries under External Strain in Iron Investigated by Molecular Dynamics Method

In the present work, the evolution of atomic structures and related changes in energy state, atomic displacement and free volume of symmetrical grain boundaries (GB) under the effects of external strain in body-centered cubic (bcc) iron are investigated by the molecular dynamics (MD) method. The res...

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Bibliographic Details
Published in:Metals (Basel ) 2022-09, Vol.12 (9), p.1448
Main Authors: Ma, Wenxue, Dong, Yibin, Yu, Miaosen, Wang, Ziqiang, Liu, Yong, Gao, Ning, Dong, Limin, Wang, Xuelin
Format: Article
Language:English
Subjects:
Analysis
Deformation
Dynamic structural analysis
Energy
Evolution
free volume
Grain boundaries
grain boundary
High temperature
Influence
Investigations
Iron
Mechanical properties
Methods
micro-cracking
Molecular dynamics
Network formation
Nucleation
Phase transitions
Simulation
Strain analysis
strain effect
Stress concentration
Tensile strength
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Summary:In the present work, the evolution of atomic structures and related changes in energy state, atomic displacement and free volume of symmetrical grain boundaries (GB) under the effects of external strain in body-centered cubic (bcc) iron are investigated by the molecular dynamics (MD) method. The results indicate that without external strain, full MD relaxations at high temperatures are necessary to obtain the lower energy states of GBs, especially for GBs that have lost the symmetrical feature near GB planes following MD relaxations. Under external strain, two mechanisms are explored for the failure of these GBs, including slip system activation, dislocation nucleation and dislocation network formation induced directly by either the external strain field or by phase transformation from the initial bcc to fcc structure under the effects of external strain. Detailed analysis shows that the change in free volume is related to local structure changes in these two mechanisms, and can also lead to increases in local stress concentration. These findings provide a new explanation for the failure of GBs in BCC iron systems.
ISSN:2075-4701
2075-4701
DOI:10.3390/met12091448