Physico-mechanical properties and micromechanisms of local deformation in thin near-surface layers of complex multiphase materials

Size effects in the local mechanical properties of multiphase materials are studied by means of micro- and nanoindentation. The numerical values of the elasticity modulus, hardness, and crack resistance of single phases and interphase boundaries in several rock samples (polycrystalline banded iron formations, granite, anthracite, sandstone, marble, and serpentine marble) are determined. The strongest and weakest intergrowth boundaries in the investigated materials are established. Thermal activation analysis is performed, and the activation and energy characteristics of local deformation in a material under an indenter are identified. The predominant micromechanisms of plasticity in single phases and inclusions in rocks under the action of high local stresses are identified.