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Interaction and Multiscale Mechanics   Volume 6, Number 3, September 2013, pages 301-316
DOI: https://doi.org/10.12989/imm.2013.6.3.301
 
Influence of indenter shape on nanoindentation: an atomistic study
Chia-Wei Lai and Chuin-Shan Chen

 
Abstract     [Buy Article]
    The influence of indenter geometry on nanoindentation was studied using a static molecular dynamics simulation. Dislocation nucleation, dislocation locks, and dislocation movements during nanoindentation into Al (001) were studied. Spherical, rectangular, and Berkovich indenters were modeled to study the material behaviors and dislocation activities induced by their different shapes. We found that the elastic responses for the three cases agreed well with those predicted from elastic contact theory. Complicated stress fields were generated by the rectangular and Berkovich indenters, leading to a few uncommon nucleation and dislocation processes. The calculated mean critical resolved shear stresses for the Berkovich and rectangular indenters were lower than the theoretical strength. In the Berkovich indenter case, an amorphous region was observed directly below the indenter tip. In the rectangular indenter case, we observed that some dislocation loops nucleated on the plane. Furthermore, a prismatic loop originating from inside the material glided upward to create a mesa on the indenting surface. We observed an unusual softening phenomenon in the rectangular indenter case and proposed that heterogeneously nucleating dislocations are responsible for this.
 
Key Words
    nanoindentation; indenter shape; berkovich indenter; dislocation; heterogeneous nucleation; molecular dynamics
 
Address
Chia-Wei Lai and Chuin-Shan Chen: Department of Civil Engineering, National Taiwan University, Taipei, Taiwan
 

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