Investigation on crack propagation in single crystal Ag with temperature dependence
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Jin Bao Wang School of Shipping, Port & Civil Engineering, Zhejiang Ocean University, Zhoushan 316022, China
Li Gang Sun Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
Ying Yan Zhang School of Computing, Engineering and Mathematics, Western Sydney University, Penrith, NSW 2751, Australia
Mei Ling Tian School of Shipping, Port & Civil Engineering, Zhejiang Ocean University, Zhoushan 316022, China
Xiao Qiao Hea) Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China (Received 14 September 2015; accepted 6 October 2015)
Crack propagation behaviors in a precracked single crystal Ag under mode I loading at different temperatures are studied by molecular dynamics simulation. The simulation results show that the crack propagation behaviors are sensitive to external temperature. At 0 K, the crack propagates in a brittle manner. Crack tip blunting and void generation are first observed followed by void growth and linkage with the main crack, which lead to the propagation of the main crack and brittle failure immediately without any microstructure evolution. As the temperature gets higher, more void nucleations and dislocation emissions occur in the crack propagation process. The deformation of the single crystal Ag can be considered as plastic deformation due to dislocation emissions. The crack propagation dynamics characterizing the microstructure evolution of atoms around the crack tip is also shown. Finally, it is shown that the stress of the single crystal Ag changes with the crack length synchronously.
I. INTRODUCTION
Many different kinds of face-centered cubic (FCC) materials such as Cu, Al, and Ni are widely used in industries, especially as structural materials. With the development of science and technology, more and more nanoscale structures made of FCC materials become significantly attractive. Different materials with the same FCC structure possibly present different failure patterns because of their different material properties such as their different vacancy-formation energies and surface energies.1 Therefore, to well apply such nanomaterials to microelectro-mechanical systems, it is essential to achieve a better understanding of their mechanical properties, deformation behaviors, and fracture modes in an atomic scale. Fracture is a complicated phenomenon caused by crack propagation. Such a process spans several scales and the
Contributing Editor: Susan B. Sinnott a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.325 J. Mater. Res., Vol. 30, No. 22, Nov 27, 2015
smallest scale is the bond-breaking between atoms. Although the continuum fracture mechanics can explain the fracture behavior well in a macroscale, it cannot be applied directly in nanoscale because the fracture behavior of materials in nanoscale mainly dependents on the local atomic environment such as the atomic structure, the lattice orientation and the discrete nature of matter distribution.1,2 Therefore
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