Effect of WC particle size on the microstructure, mechanical properties and fracture behavior of WC-(W, Ti, Ta) C-6 wt% Co cemented carbides

This study deals with the microstructure and mechanical properties of WC-(W, Ti, Ta) C-9 vol.% Co cemented carbides fabricated by conventional sintering. The conventional WC particles of 4 mu m size and ultrafine particles of 0.2 mu m were introduced in the system with varying ratio. The ratios of conventional WC particles to ultrafine WC particles were 2:1, 1:1, and 1:2. The microstructures of sintered WC-(W, Ti, Ta) C-9 vol.% Co cemented carbides were sensitively dependent on the ratio of conventional WC particles to ultrafine WC particles. The rim phase increased with the increase in the amount of ultrafine particles. Hardness of WC-(W, Ti, Ta) C-9 vol.% Co cemented carbide increased with increase in the amount of rim phase and decrease in the average grain size of WC particles. The bending strength showed the similar trend of the hardness. The fracture morphologies are reported. The fracture behavior changed from mixed mode to transgranular fracture mode, when the ratio of conventional WC particles to ultrafine WC particles was changed from 2:1 to 1:2. (C) 2006 Elsevier Ltd. All rights reserved.