Mechanical characterization of hard phases by means of nanoindentation

Hard phases are important features of wear-resistant materials. Hard metals and most tool steels thus consist of a high amount of hard phases, such as carbides and nitrides embedded in a softer metallic matrix. The mechanical properties and wear resistance of the system are controlled by the mechanical properties of the hard phases and the matrix. Since hard phases are brittle and have sizes in the range of microns, mechanical characterization with standard test methods, such as the tensile test, is often impossible. Nanoindentation, however, can be used to determine important mechanical parameters, such as hardness or Young’s modulus, of brittle phases on a small scale. This paper deals with the mechanical characterization of different hard phases (NbC, VC, TiC, and WC) using nanoindentation. The measurements reveal significant differences in the mechanical properties and deformation behavior of the investigated phases. The deformation behavior was investigated using atomic force microscopy (AFM) and scanni g electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) analysis for the determination of chemical composition. The influence of the matrix on the indentation result of small hard phases embedded in a softer metallic matrix was evaluated using finite element method (FEM) simulations. These simulations give an insight into the complex deformation behavior during indentation of an embedded hard phase. (AU) Copyright © 2018 Companhia Brasileira de Metalurgia e Mineração (CBMM) All rights reserved