Interaction between phase transformations and dislocations at incipient plasticity of monocrystalline silicon under nanoindentation

JJ Zhang and JG Zhang and ZF Wang and A Hartmaier and YD Yan and T Sun, COMPUTATIONAL MATERIALS SCIENCE, 131, 55-61 (2017).

DOI: 10.1016/j.commatsci.2017.01.043

Structural phase transformation and dislocation slip are two important deformation modes of monocrystalline silicon. In the present work, we elucidate mechanisms of inhomogeneous elastic-plastic transition in spherical nanoindentation of monocrystalline silicon by means of Molecular dynamics simulations. The Stillinger-Weber potential is utilized to present simultaneous phase transformations and dislocation activities in the silicon nanoindentation. And a bond angle analysis- based method is proposed to quantitatively clarify silicon phases. The influence of crystallographic orientation on the silicon nanoindentation is further addressed. Our simulation results indicate that prior to the "Pop-In" event, Si(010) undergoes inelastic deformation accompanied by the phase transformation from the Si-I to the Si-III/ Si-XII, which is not occurred in Si(110) and Si(111). While the phase transformation from the Si-I to the bct-5 is the dominant mechanism of incipient plasticity for each crystallographic orientation, dislocation nucleation is also an operating deformation mode in the elastic-plastic transition of Si(010). Furthermore, interactions between phase transformations and dislocations are more pronounced in Si (010) than the other two crystallographic orientations. (C) 2017 Elsevier B.V. All rights reserved.

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