| About this Abstract |
| Meeting |
MS&T23: Materials Science & Technology
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| Symposium
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Integration between Modeling and Experiments for Crystalline Metals: From Atomistic to Macroscopic Scales V
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| Presentation Title |
Effects of Defects on Stress- and Thermally-induced Martensitic Transformation of Nanocrystalline NiTi Alloys: A Molecular Dynamics Study |
| Author(s) |
Zhihao Zhao, Jianping Lin, Yao Xiao, Junying Min |
| On-Site Speaker (Planned) |
Zhihao Zhao |
| Abstract Scope |
In this work, the effects of dislocation, the content of vacancy and element segregation on stress- and thermally-induced martensitic transformation (MT) of nanocrystalline (Grain size = 15 nm) NiTi alloys were investigated quantitatively by molecular dynamics (MD) simulation. Results show that when the dislocation density ≤ 5 E16 m-2, the dislocation promotes stress- and thermally-induced MT, and when it is greater than 5 E16 m-2, it inhibits. Due to the coupling effect of external loading and internal stress caused by dislocations, favorable martensite variants may transition to unfavorable variants during stress-induced MT. The pinning of disordered atoms caused by vacancies strongly hinders the nucleation of martensite and the merging of martensite domains. MT can be suppressed by the local atomic strain field produced by segregation. The inhibition of vacancy on MT is much stronger than segregation at the same point defect content. |