Hardness of Constituent Phases in Ti(C_0.7N_0.3)-WC-Ni Cermets Measured by Nanoindentation

Abstract

The constituent phases in Ti(C 0.7 N 0.3 )-xWC-20Ni (wt%, x=5, 15, 25) cermets were characterized using nanoindentation in conjunction with observation of microstructure. The microstructure of cermet is composed of hard phase and binder phase, which gave rise to a wide range of hardness distribution when nanoindentation was carried out on the polished surface of cermets. Because of the inhomogeneous nature of cermet microstructure, observation of indented surface was indispensable in order to separate the hardness of each constituent phase. The measured values of hardness using nanoindentation were ~14 ㎬ for the binder phase and ~24 to 28 ㎬ for the hard phase, of which nanoindentation hardness was decreased with the addition of WC into Ti (C 0.7 N 0.3 )-Ni system. In addition, the nanoindentation hardness of Ni binder phase was much higher than reported Vickers hardness, which could result from confined deformation of binder phase due to the surrounding hard phase particles.