Atomistic Simulation Study on the Tensile Deformation Behaviour of Nanocrystalline Ni

Abstract:

Using molecular dynamics simulations, the influence of transverse tensile stresses on the plastic deformation behaviour of nanocrystalline (NC) Ni under tension has been investigated. The sample with an average grain size of 20 nm was created using a Voronoi construction, and two different tensile tests of the sample were performed at a constant strain rate. The simulation results revealed that more partials were emitted from the grain boundaries and propagate into the grain interiors after adding the transverse tensile stress, enhancing the dislocation density in the grain interiors. This increased dislocation density can cause additional strain hardening observed in the stress strain curve. Meanwhile, it was observed from microstructures that nanovoids are easier to form and coalesce into cracks under the biaxial stress state, causing strain softening. The two competing effects of the transverse tensile stress on the plastic deformation behaviour of NC Ni resulted in the flow stresses from 4% to 10% strain in the biaxial stress state slightly larger than those in the uniaxial stress state.

• Periodical: Materials Science Forum (Volumes 745-746)
• Pages: 315-320
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.745-746.315
• Online since: February 2013
• Authors: Wen Bin Li, Fu Ping Yuan, Xiao Lei Wu
• Keywords: Molecular Dynamics (MD) Simulation, Nanocrystalline Materials, Plastic Deformation, Stress States

References

[1] K.S. Kumar, H. Van Swygenhoven, S. Suresh. Mechanical behavior of nanocrystalline metals and alloys. Acta Mater. 51 (2003) 5743-5774.

DOI: 10.1016/j.actamat.2003.08.032

[2] M.A. Meyers, A. Mishra, D.J. Benson. Mechanical properties of nanocrystalline meterials. Prog. Mater. Sci. 51 (2006) 427-556.

[3] E. Ma, Instabilities and ductility of nanocrystalline and ultrafine-grained metals. Scr. Mater. 49 (2003) 663-668.

DOI: 10.1016/s1359-6462(03)00396-8

[4] T.H. Fang, W.L. Li, N.R. Tao, K. Lu. Revealing extraordinary intrinsic tensile plasticity in gradient nano-grained copper. Science. 331 (2011) 1587-1590.

DOI: 10.1126/science.1200177

[5] S.L. Semiatin, H.R. Piehler, Deformation of sandwich sheet materials in uniaxial tension. Metall. Trans. A. 10 (1979) 85-96.

DOI: 10.1007/bf02686411

[6] Y. Xiang, T. Li, Z.G. Suo, J.J. Vlassak, High ductility of a metal film adherent on a polymer substrate. Appl. Phys. Lett. 87 (2005) 161910.

DOI: 10.1063/1.2108110

[7] A.C. Lund, T.G. Nieh, C.A. Schuh, Tension/compression strength asymmetry in a simulated nanocrystalline metal. Phys. Rev. B 69 (2004) 012101.

DOI: 10.1103/physrevb.69.012101

[8] A.C. Lund, C.A. Schuh, Strength asymmetry in nanocrystalline metals under multiaxial loading. Acta Mater. 53 (2005) 3193-3205.

DOI: 10.1016/j.actamat.2005.03.023

[9] Y. Lu, J. Song, J.Y. Huang, J. Lou, Fracture of sub-20nm ultrathin gold nanowires. Adv. Funct. Mater. 21 (2011) 3982-3989.

DOI: 10.1002/adfm.201101224

[10] Y. Mishin, D. Farkas, M.J. Mehl, D.A. Papaconstantopoulos, Interatomic potentials for monoatomic metals from experimental data and ab initio calculations. Phys. Rev. B. 59 (1999) 3393-3407.

DOI: 10.1103/physrevb.59.3393

[11] S. Brandstetter, H. Van Swygenhoven, et al., From micro- to macroplasticity. Adv. Mater. 18 (2006) 1545-1548.

DOI: 10.1002/adma.200600397

[12] H. Van Swygenhoven, P.M. Derlet, A.G. Froseth, Stacking fault energies and slip in nanocrystalline metals. Nature Mater. 3 (2004) 399-403.

DOI: 10.1038/nmat1136

[13] X.L. Wu, Y.T. Zhu, Y.G. Wei, Q. Wei, Strong strain hardening in nanocrystalline nickel. Phys. Rev. Lett. 103 (2009) 205504.

DOI: 10.1103/physrevlett.103.205504

[14] E. Bitzek, C. Brandl, P.M. Derlet, H.V. Swygenhoven, Dislocation cross-slip in nanocrystalline fcc metals. Phys. Rev. Lett. 100 (2008) 235501.

DOI: 10.1103/physrevlett.100.235501