EPMA and GDOES in functional-gradient hardmetal systems

WDS-EPMA and GDOES measurements were applied for the characterization of the in-situ surface modification process of (Ti, W)C-based hard-metals by in-diffusion of carbon and nitrogen leading to complicated microstructures composed by layers and/or gradients. The calibration of the analytical techniques was performed with chemically characterized specimens prepared by diffusional techniques or hot-pressing. In addition, for the GDOES method, certified reference materials (CRMs) have been used. The work was started from a re-investigation of the W-C and Mo-C systems in order to measure homogeneity regions of the various phases prepared by use of diffusion couples. Subsequently, the metal and non-metal contents of various sequences of layers and/or gradients in functional-gradient hardmetals (FGHs) were measured. Both methods were employed as complementary tools to get information about the element-concentration distribution in FGHs so that a better understanding of the influence of process parameters for fabrication of special hardmetals is possible.