Preparation and mechanical properties of bulk ultrafine (W 0.5 Al 0.5 )C 0.65 with minor Fe binder by reactive hot-pressing

Abstract

Binderless (W_0.5Al_0.5)C_0.65 produced by reactive hot-pressing (RHP) has high hardness but low bending strength and fracture toughness. In this work, bulk ultrafine (W_0.5Al_0.5)C_0.65 with minor addition of Fe as the binder phase has been prepared by RHP. Rapid synthesis and high densification can be achieved for the (W_0.5Al_0.5)C_0.65 with 0.4–1.0 wt-%Fe by RHP at a relatively low temperature. Pure (W_0.5Al_0.5)C_0.65 without sub-carbide phase or brittle η-type phase can be synthesised due to the fact that the carbon vacancy in (W_0.5Al_0.5)C _y can reach 50%. And thanks to the combined effect of nanoscaled initial powders, low temperature, rapidly reactive sintering and pressure, bulk ultrafine (W_0.5Al_0.5)C_0.65-Fe with a grain size of about 0.2 μm can be obtained by RHP. Thus, with an appropriate amount of Fe (about 0.8 wt-% in this work), the bending strength and fracture toughness of (W_0.5Al_0.5)C_0.65 can be highly improved.