Measurement of Hardness of Constituent Phases in Ti(C_0.7N_0.3)-NbC-Ni Cermets Using Nanoindentation

Abstract

The indentation technique has been one of the most commonly used techniques for the measurement of the mechanical properties of materials due to its experimental ease and speed. Recently, the scope of indentation has been enlarged down to the nanometer range through the development of instrumentations capable of continuously measuring load and displacement. In addition to testing hardness, the elastic modulus of submicron area could be measured from an indentation load-displacement (P-h) curve. In this study, the hardness values of the constituent phases in Ti(C 0.7 N 0.3 )-NbC-Ni cermets were evaluated by nanoindentation. SEM observation of the indented surface was indispensable in order to separate the hardness of each constituent phase since the Ti(C 0.7 N 0.3 )-based cermets have relatively inhomogeneous microstructure. The measured values of hardness using nanoindentation were ~20 GPa for hard phase and ~10 GPa for binder phase. The effect of NbC addition on hardness was not obvious in this work.