Microstructures, densification and mechanical properties of T1C-Al_2O_3-Al composite by field-activated combustion synthesis

摘要

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 A1_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 MPam~(1/2), respectively.