Mapping of mechanical properties of WC–Co using nanoindentation

Abstract

High-resolution measurements of mechanical properties are of immense importance in metallurgy. Measuring the intrinsic properties of each phase separately in multiphase materials gives information that is valuable for the development of new materials and for modelling. In this work, nanoindentation has been used to reveal mechanical properties of different phases in WC–Co with very high resolution. The resolution limits of the equipment and this material as well as various techniques to accomplish the measurements were evaluated. By making indents only 0.1 µm apart and using very low loads (1 mN) it was possible to distinguish between the two different phases, WC and Co. Maps created from the measured properties, hardness and Young’s modulus, were in excellent agreement with SEM images of the same area. Furthermore, it was also possible to detect an increased hardness of the Co binder phase by a factor of four as compared to the bulk hardness of Co. This work verifies experimentally what several authors have proposed earlier based on modelling.