Synthesis of Ternary Machinable AI_2O_3/Ti_2AIC Composites by High Energy Mmilling and in-Situ Hot-Pressing Method

摘要

Al_2O_3/Ti_2AlC composites were synthesized by high energy milling and hot-pressing at 1200 C in a vacuum furnace with a pressure of 4.8×10～(-2) Pa, using Ti, Al and C powder as raw materials. The effect of sintering temperature on the reactions, phase composition and microstructure of the synthesized products were investigated. The results show that the TiC and TiAl intermetallics composite powders were synthesized during the milling process. After the hot pressing, Ti_2AlC phase was formed by the reaction between TiC and TiAl. A small amount of Al_2O_3 was also produced because of the oxidation of Al in the hot press process, which formed Al_2O_3/Ti_2AlC composite together with the Ti_2AlC at 1200°C. The fine grained Al_2O_3 particles disperse within Ti_2AlC uniformly, which play a important role to strengthen Ti_2AlC matrix, resulting in the increase of flexural strength and fracture toughness from 250 to 275.4MPa, 9.8 to 10.5MPa·m～(l/2), respectively.