Microstructure and composition of the grain/binder interface in WC–Ni3Al composites

• A preferential orientation relationship between WC and Ni3Al has been found.
• The preferential orientation relationship shows a good coherence.
• WC/Ni3Al interface has a sharper compositional gradient than WC/Co interface.
• WC/Ni3Al interface has a narrower transition region than WC/Co interface.

The microstructure and composition of WC/Ni3Al interface were studied. An orientation relationship of [100]WC//[110]Ni3Al and (001)WC//(001)Ni3Al with a good coherence, besides many random orientation relationships between WC and Ni3Al, has been repetitively found by selected area electron diffraction and high resolution TEM observations. The XRD pattern of WC–Ni3Al composites indicated that the major binder phase was Ni3Al and showed possibility of coherence between WC and Ni3Al as common interplanar spacings existed. Electron probe microanalysis results revealed that the atomic ratio of Al:Ni is close to 1:3 in binder phase and WC/Ni3Al interface in the WC–Ni3Al composites has a sharper compositional gradient and a smaller width of transition region than the WC/Co interface in WC–Co composites.