Crystal orientation dependence of crack growth and stress evolution in single crystal nickel: a molecular dynamics simulation-based cohesive zone model
Y Qi and WP Wu and YB Chen and MX Chen, RSC ADVANCES, 5, 65942-65948 (2015).
The crack growth and stress evolution of single crystal nickel under three different crystal orientations (X 100, Y010, Z001; X110, Y(1) over bar 10, Z001; X111, Y(1) over bar 10, Z (1) over bar(1) over bar2) were studied by introducing a cohesive zone model (CZM) based on molecular dynamics (MD) simulation. The results indicated that different crystal orientations have significant effect on the fracture mechanisms and stress distribution characteristics. Under the X100, Y010, Z001 orientation, void nucleation and growth was observed during the crack propagation; under the X110, Y(1) over bar 10, Z001 orientation, atomic configurations basically remained unchanged throughout the crack growth, which represented a brittle process; dissimilarly, blunting and slip bands occurred at the front of the crack tip for the X111, Y(1) over bar 10, Z(1) over bar(1) over bar2 orientation. These different mechanisms resulted in different stress distributions along the crack path and crack growth rates. Moreover, based on the calculation of the CZM, the relationship between stress and opening displacement was obtained, which provided useful information for understanding the crystal orientation dependent on the atomic-scale fracture mechanisms and associated mechanical properties.
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