Microstructures, densification and mechanical properties of TiC–Al 2O 3–Al composite by field-activated combustion synthesis

Abstract

Dense TiC–Al 2O 3–Al composite was prepared with Al, C and TiO 2 powders by means of electric field-activated combustion synthesis and infiltration of the molten metal (here Al) into the synthesized TiC–Al 2O 3 ceramic. An external electric field can effectively improve the adiabatic combustion temperature of the reactive system and overcome the thermodynamic limitation of reaction with x < 10 mol. Thereby, it can induce a self-sustaining combustion synthesis process. During the formation of Al 2O 3–TiC–Al composite, Al is molten first, and reacted with TiO 2 to form Al 2O 3, followed by the formation of TiC through the reaction between the displaced Ti and C. Highly dense TiC–Al 2O 3–Al with relative density of up to 92.5% was directly fabricated with the application of a 14 mol excess Al content and a 25 V cm −1 field strength, in which TiC and Al 2O 3 particles possess fine-structured sizes of 0.2–1.0 μm, with uniform distribution in metal Al. The hardness, bending strength and fracture toughness of the synthesized TiC–Al 2O 3–Al composite are 56.5 GPa, 531 MPa and 10.96 MPa m 1/2, respectively.