Synthesis and characterization of Ti3(Al1-nGen)C2 by a reactive hot pressing of TiCx, Al, and Ge powder mixture

Abstract

Ti3(Al1-nGen)C2 (n=0, 0.3, 0.5, 0.7, 1.0)were synthesized by a reactive hot pressing of TiCX (x=0.6), Al and Ge powder mixture at 1400 ºC for 1 h under 25 MPa. A series of bulk Ti3(Al1-nGen)C2 was successfully fabricated by a direct liquid-solid reaction between Al-Ge melt and TiCx , and simultaneous densification. It was found that the lattice parameter c was linearly decreased but the lattice parameter a was not changed with an increase of Ge contents in Ti3(Al1-nGen)C2 . The synthesis mechanism of Ti3(Al1-nGen)C2 by a direct reaction between TiCx and Al-Ge melt was discussed. Synthesized bulk Ti3(Al1-nGen)C2 was maintained a typical layered structure as shown in other ternary carbide such as Ti3AlC2, Ti3SiC2 and Ti3GeC2. With increasing Al contents in Ti3(Al1-nGen)C2, Vickers hardness and flexural strength of Ti3(Al1-nGen)C2 were increased due to the solution hardening in Ge layer in the crystalline structure. The flexural strength of Ti3(Al1-nGen)C2 (n=0.3) was about 600 MPa, which was about 3 times higher than that of Ti3GeC2. The Vickers hardness was slightly decreased with increasing indentation load.