Microstructure, mechanical properties and fracture behavior of WC-40 vol.% Ni3Al composites with various carbon contents

Abstract

In this paper, the effect of the carbon contents on the microstructure, mechanical properties and fracture behavior of WC-40vol.% Ni3Al composites prepared by conventional powder metallurgy was studied. Microstructure examinations of WC-40vol.% Ni3Al specimens indicated that the WC grain is round and fine compared with faceted and large WC grain of WC-Co composites. With increasing carbon contents, the WC morphology of WC-40vol.% Ni3Al composites is similar and the size of WC grain is approximate and the distribution of binder phase becomes relatively uniform. Furthermore, composition analysis of binder phase showed that, with the increase of carbon content, the solubility of W in Ni3Al reduced slightly. The ~9wt.% solubility of W in Ni3Al is much lower compared with ~22.4wt.% of WC-40vol.% Co composites. The hardness and transverse rupture strength of WC-40vol.% Ni3Al composites decrease with increasing carbon contents slightly. WC-40vol.% Ni3Al composites present higher hardness and lower transverse rupture strength than that of WC-40vol.% Co composites. With increasing carbon contents, the fracture behavior of the WC-40vol.% Ni3Al composites is affected greatly and the fracture mode changes from transgranular fracture towards intergranular fracture.