| Directionally solidified WC-W2C ceramics containing 40 at % carbon, corresponding to the WC-W2C eutectoid composition, were produced by laser surface melt processing. The resulting microstructures showed a lamellar-type eutectic/eutectoid microstructure with the WC minor phase embedded in the W2C matrix phase. The interlamellar spacing (lambda) in the eutectoid regions followed the relationship Vlambda 3.8 = constant, with the smallest spacing of 331&;Crystallographic orientation relationships and interfaces in directionally solidified WC-W2C eutectoids were investigated by electron microscopy and electron backscattered diffraction. A preferred nominal growth directions of [1210] WC// [12 10] W2C or [0110]WC//[01 10]W2C along the solidification direction was observed. The majority of interface habit planes are found to be (0001)WC//(0001)W 2C. The interfaces were found to be semicoherent, with a misfit Burger&;Indentation-induced deformation mechanisms in directionally solidified WC-W2C eutectoids were investigated via scanning electron microscopy and transmission electron microscopy. Palmquist crack profiles were observed at indentation loads equal or higher than 4.9 N in all samples. Distinct deformation mechanisms were observed in W2C-rich regions, primary WC regions, and WC-W2C eutectoid regions. Shear banding dominates in deformed W2C-rich region, whereas dislocation-stacking fault networks were found in deformed primary WC region. In the eutectoid regions, deformation was primarily observed in the WC lamellae, where majority of dislocations had the Burger's vector of . |
