Interplay of dislocation-based plasticity and phase transformation during Si nanoindentation

ZB Zhang and A Stukowski and HM Urbassek, COMPUTATIONAL MATERIALS SCIENCE, 119, 82-89 (2016).

DOI: 10.1016/j.commatsci.2016.03.039

Nanoindentation into single-crystalline Si is modeled by molecular dynamics simulation using a modified Tersoff potential. We observe that the high stress produced during indentation leads to three processes occurring consecutively in the substrate: (i) phase transformation of the original cubic diamond (cd) to the bct5 phase; (ii) generation of dislocations; and (iii) amorphization. The bct5 phase develops along 111 planes of the cd phase; when these meet, the enclosed volume of cd phase transforms to bct5. The particular role played by a stable tetrahedral structure formed by bct5 111 planes and 111 intrinsic stacking faults in the cd structure is highlighted. The phase transformation to bct5 is partially reversed when dislocations nucleate in the cd phase and locally relieve stresses. The generation and reactions of the uncommon dislocations 1/4 < 111 > and 1/3 < 112 > are discussed. (C) 2016 Elsevier B.V. All rights reserved.

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