›› 2014, Vol. 23 ›› Issue (9): 98102-098102.doi: 10.1088/1674-1056/23/9/098102

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    下一篇

Effect of stress state on deformation and fracture of nanocrystalline copper:Molecular dynamics simulation

张亮, 吕程, Kiet Tieu, 裴林清, 赵星   

  1. School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
  • 收稿日期:2014-01-14 修回日期:2014-03-12 出版日期:2014-09-15 发布日期:2014-09-15
  • 基金资助:
    Project supported by the Research Council Discovery Projects of Australia (Grant No. DP0773329).

Effect of stress state on deformation and fracture of nanocrystalline copper:Molecular dynamics simulation

Zhang Liang (张亮), Lü Cheng (吕程), Kiet Tieu, Pei Lin-Qing (裴林清), Zhao Xing (赵星)   

  1. School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
  • Received:2014-01-14 Revised:2014-03-12 Online:2014-09-15 Published:2014-09-15
  • Contact: Lü Cheng E-mail:chenglu@uow.edu.au
  • Supported by:
    Project supported by the Research Council Discovery Projects of Australia (Grant No. DP0773329).

摘要: Deformation in a microcomponent is often constrained by surrounding joined material making the component under mixed loading and multiple stress states. In this study, molecular dynamics (MD) simulation are conducted to probe the effect of stress states on the deformation and fracture of nanocrystalline Cu. Tensile strain is applied on a Cu single crystal, bicrystal and polycrystal respectively, under two different tension boundary conditions. Simulations are first conducted on the bicrystal and polycrystal models without lattice imperfection. The results reveal that, compared with the performance of simulation models under free boundary condition, the transverse stress caused by the constrained boundary condition leads to a much higher tensile stress and can severely limit the plastic deformation, which in return promotes cleavage fracture in the model. Simulations are then performed on Cu single crystal and polycrystal with an initial crack. Under constrained boundary condition, the crack tip propagates rapidly in the single crystal in a cleavage manner while the crack becomes blunting and extends along the grain boundaries in the polycrystal. Under free boundary condition, massive dislocation activities dominate the deformation mechanisms and the crack plays a little role in both single crystals and polycrystals.

关键词: molecular dynamics, nanocrystalline, stress state, deformation mechanism

Abstract: Deformation in a microcomponent is often constrained by surrounding joined material making the component under mixed loading and multiple stress states. In this study, molecular dynamics (MD) simulation are conducted to probe the effect of stress states on the deformation and fracture of nanocrystalline Cu. Tensile strain is applied on a Cu single crystal, bicrystal and polycrystal respectively, under two different tension boundary conditions. Simulations are first conducted on the bicrystal and polycrystal models without lattice imperfection. The results reveal that, compared with the performance of simulation models under free boundary condition, the transverse stress caused by the constrained boundary condition leads to a much higher tensile stress and can severely limit the plastic deformation, which in return promotes cleavage fracture in the model. Simulations are then performed on Cu single crystal and polycrystal with an initial crack. Under constrained boundary condition, the crack tip propagates rapidly in the single crystal in a cleavage manner while the crack becomes blunting and extends along the grain boundaries in the polycrystal. Under free boundary condition, massive dislocation activities dominate the deformation mechanisms and the crack plays a little role in both single crystals and polycrystals.

Key words: molecular dynamics, nanocrystalline, stress state, deformation mechanism

中图分类号:  (Molecular nanostructures)

  • 81.07.Nb
81.07.Bc (Nanocrystalline materials) 81.40.Vw (Pressure treatment) 81.40.Jj (Elasticity and anelasticity, stress-strain relations)