Growth Behavior of WC Grains in Ni<sub>3</sub>Al Matrix during Liquid Phase Sintering

Abstract

Growth behavior of WC grains with two different sizes of 10 μm and 4 μm in the same liquid matrix has been studied in the WC–40vol.%Ni3Al system. The samples were sintered under a carbon saturated condition. Surfaces of the coarse WC grains are strongly micro-faceted and stepped. With the increase of sintering time, the average size of the fine WC grain increases continuously and very large plate-like triangular prismatic WC grains appear. The present investigation thus shows that the growth behavior of fine WC grain is affected by lower solubility of W in Ni3Al matrix and the abnormal growth of WC grains is suppressed. However, the growth behavior of coarse WC grain is governed only by the difference in energy between the facets.