ABSTRACT

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.