Initiation of a plastic flow in boron carbide at nanoindentation

The initiation of a plastic flow in nanodeformation of crystalline boron carbide sample has been studied by nanoindentation. An abrupt elastoplastic transition (pop-in) at the indenter penetration into boron carbide as a result of a homogeneous nucleation of dislocations in the imprint region has been observed for the first time. The experimental assessment of the theoretical shear strength and ultimate hardness of boron carbide has been made possible by the analysis of the nanoindentation data for a homogeneous nucleation of dislocation in the imprint region.