High resolution STEM investigation of interface layers in cemented carbides. (April 2018) - Meingast, Arno
Abstract: Cemented carbides with sub-micron grain size have increased the need to restrict grain growth during sintering. Commonly used inhibitors like V, Ti, and Cr have been observed to form interface layers in the interfaces between WC grains and the Co binder. Atomistic modeling has predicted the composition and thickness of the interface layers. Earlier, the interface layers have been characterized qualitatively using high resolution transmission electron microscopy (TEM). To get more information about the structure and composition of the interface layers in a Ti containing cemented carbide in this work, Z contrast imaging and spectroscopy using scanning transmission electron microscopy (STEM) have been combined. Elemental maps revealing the structure of the interface layers will be presented. Highlights: Ti selectively segregates to basal WC planes only despite Ti-saturated Co binder. Two interfacial monolayers between the WC and Co binder were verified by STEM HAADF. STEM-EDXS proved the stacking order to be a Ti-rich followed by a W-rich monolayer.