Atomistic-continuum simulation of nano-indentation in molybdenum

Simulations of nano-indentation in bcc molybdenum are performed using a coupled atomistic-continuum method and a multi-body interatomic potential which includes angular forces. The indenter is flat and rigid while the indented material is a single crystal having its (100) and (111) directions respectively parallel to the indentation direction, in separate simulations. Indentation is accommodated by elastic deformation of the surface, up to an indenter displacement of about 6 Angstrom, and by nucleation of crystalline defects for deeper indents. When indented in the (100) direction, the crystal twins under the indenter, while indentation in the (111) direction produces dislocation nucleation from the stress concentration sites at the indenter edge. The critical loads for these events are computed and the nucleation mechanism is observed. The results are compared with available experimental data.