Synthesis and mechanical properties of Ti3AlC2 by hot pressing TiCx/Al powder mixture

Abstract

A study has been performed to synthesize polycrystalline bulk Ti3AlC2 by hot pressing from TiCx (x = 0.6) and Al powder mixture at the temperature range of 800-1600 degrees C under 25 MPa for various times. Relatively pure Ti3AlC2 was successfully synthesized above 900 degrees C. Small amount of Ti2AlC as a secondary phase was observed along with Ti3AlC2 below 1400 degrees C. With increasing hot pressing time to 1250 degrees C, the amount of un-reacted TiC, was gradually decreased while Ti3AlC2 was appeared to be a dominant phase. The densification of Ti3AlC2 was examined as a function of hot pressing temperature up to 1600 degrees C as well as it was investigated with hot pressing time at 1250 degrees C. Near fully dense Ti3AlC2 was synthesized as the hot pressing time was increased at 1250 degrees C. Fully dense and pure Ti3AlC2 could be synthesized by hot pressing above 1400 degrees C. The resulting Ti3AlC2 above 1400 degrees C showed the typical laminated and platelet grain structure of ternary carbides. With increasing processing temperature to 1600 degrees C, the typical platelet grain structure of Ti3AlC2 was started to be destroyed and significant grain coarsening was occurred, which might be caused by partial melting of Ti3AlC2. The Vickers hardness of bulk Ti3AlC2 was about 3.5-6 GPa under the loading of ION. The maximum flexural strength of synthesized bulk Ti3AlC2 Was over 900 MPa. The new process using TiCx/Al powder mixture as a starting material made it possible to shorten the synthesis time, to reduce processing temperature, as well as to improve the flexural strength of Ti3AlC2. (c) 2007 Elsevier Ltd. All rights reserved.