Methods of Micro- and Nanoindentation for Characterization of Local Physical and Mechanical Properties of Multiphase Materials

摘要

Processes of local deformation and fracture of the surface of a number of rocks (ferruginous quartzite, granite, marble, serpentine, anthracite, sandstone) are studied by means of micro- and nanoindentation under high local loadings. Numerical values of elastic, plastic and strength (hardness, Young's modulus, fracture toughness, etc.) properties of rock specimens are defined in a wide range of loads and indentation depth h (from 10 nm to 50 μm). The influence of size effects on hardness is studied, including in other physical and mechanical properties of individual phases and interphase boundaries of a wide range of rocks. Moreover, nonmonotonic dependences of hardness of certain mineral components of studied rock specimens are identified on the micro- and nanoscale. It is found that the hardness of individual mineral phases naturally increases with decreasing indentation depth up to 60-120 nm depending on the type of a rock specimen and the phase type, and then begins falling. Values of the coefficient of fracture toughness, separate mineral phases and interphase fusion boundaries of different types are identified. It is revealed that hematite in ferruginous quartzite has the greatest value of the fracture toughness factor while anthracite has the lowest one. The strongest ones are boundaries of fusion of mineral components of ferruginous quartzite and the lowest ones are boundaries of individual phase fusion in anthracite.