Tension-Compression Asymmetry in Mechanical Behavior and Crystal Defect of Thin Ni/Ni3Al (001) Nanowires

JG Yu and QX Zhang, RARE METAL MATERIALS AND ENGINEERING, 43, 1803-1808 (2014).

Molecular dynamics (MD) simulations were employed to study the asymmetry in mechanical behavior and crystal defect of thin Ni/Ni3Al (001) nanowires (NWs) under tension and compression. The stress-strain responses and crystal defects of the thin Ni/Ni3Al (001) NWs were compared at different temperatures. The simulation results indicate that the Schmidt factor of the leading partial dislocation under tensile loading condition is larger than that under compression. The flow stress presents abnormal behavior at 10 K under compression. The thin Ni/Ni3Al (001) NW is stronger in compression than in tension at different temperatures. These results present significant tension-compression asymmetry. In addition, the stacking faults enhance atomic shuffling and a partial dislocation is emitted from the stacking fault. Atomic shuffling plays an important role in stimulating the dislocation emission. Furthermore, we also have found that the evolution of different crystal defects is mainly point dislocations and stacking faults. The thin Ni/Ni3Al (001) NWs give rise to stacking faults on all four possible 111 orientations under tension and compression. Generally, studying of the relation between the tension-compression asymmetry and the temperature of thin Ni/Ni3Al (001) NWs at different temperatures can help us further understand the mechanical properties accurately and completely.

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