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Phase Transition in Iron Thin Films Containing Coherent Twin Boundaries: A Molecular Dynamics Approach

School of Material Science and Engineering, Shanghai Institute of Technology, Haiquan Road 100, Shanghai 201418, China
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Materials 2020, 13(16), 3631; https://doi.org/10.3390/ma13163631
Received: 6 July 2020 / Revised: 3 August 2020 / Accepted: 14 August 2020 / Published: 17 August 2020
Using molecular dynamics (MD) simulation, the austenitic and martensitic phase transitions in pure iron (Fe) thin films containing coherent twin boundaries (TBs) have been studied. Twelve thin films with various crystalline structures, thicknesses and TB fractions were investigated to study the roles of the free surface and TB in the phase transition. In the austenitic phase transition, the new phase nucleates mainly at the (112)bcc TB in the thicker films. The (111¯)bcc free surface only attends to the nucleation, when the film is extremely thin. The austenitic transition temperature shows weak dependence on the film thickness in thicker films, while an obvious transition temperature decrease is found in a thinner film. TB fraction has only slight influence on the austenitic temperature. In the martensitic phase transition, both the (1¯10)fcc free surface and (111)fcc TB attribute to the new body-center-cubic (bcc) phase nucleation. The martensitic transition temperature increases with decreased film thickness and TB fraction does not influent the transition temperature. In addition, the transition pathways were analyzed. The austenitic transition obeys the Burgers pathway while both the Kurdjumov–Sachs (K–S) and Nishiyama–Wassermann (N–W) relationship are observed in the martensitic phase transition. This work may help to understand the mechanism of phase transition in the Fe nanoscaled system containing a pre-existing defect. View Full-Text
Keywords: solid–solid phase transition; iron thin film; free surface; twin boundary; molecular dynamics simulation solid–solid phase transition; iron thin film; free surface; twin boundary; molecular dynamics simulation
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MDPI and ACS Style

Wang, B.; Jiang, Y.; Xu, C. Phase Transition in Iron Thin Films Containing Coherent Twin Boundaries: A Molecular Dynamics Approach. Materials 2020, 13, 3631. https://doi.org/10.3390/ma13163631

AMA Style

Wang B, Jiang Y, Xu C. Phase Transition in Iron Thin Films Containing Coherent Twin Boundaries: A Molecular Dynamics Approach. Materials. 2020; 13(16):3631. https://doi.org/10.3390/ma13163631

Chicago/Turabian Style

Wang, Binjun, Yunqiang Jiang, and Chun Xu. 2020. "Phase Transition in Iron Thin Films Containing Coherent Twin Boundaries: A Molecular Dynamics Approach" Materials 13, no. 16: 3631. https://doi.org/10.3390/ma13163631

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