Synthesis and characterization of quarternary Ti3Si(1-x)AlxC2 MAX phase materials

Ti3Si(1-x)AlxC2 (x=0-1) quarternary MAX phase materials were prepared by spark plasma sintering of TiC, Ti, Si and Al powder mixtures at 1200 degrees C. Effect of Al addition on lattice parameters, density and hardness were investigated. Impurities are limited to binary phases of TiC and Ti5Si3. No multinary compound other than Ti3Si(1-x)AlxC2 can be detected. TiC exists as impurity in all samples and trace amount of Ti5Si3 can be detected in Samples x=0.1-0.6. Oxidation of Al cannot be avoided although all sintering were performed under vacuum and trace amount of Al2O3 can be found in all samples with Al addition. Experimental results show that the lattice parameters a and c increase linearly with increasing Al content for x=0-1. The lattice variations are strongly anisotropic and follow Vegard's law. Both density and hardness decrease as Al content increases. The linear variation of lattice parameters, d spacings of crystalline faces and density against Al concentration suggest that continuous solid solutions of Ti3Si(1-x)AlxC2 (x=0-1) may have been formed between Ti3SiC2 and Ti3AlC2. (C) 2015 Published by Elsevier Ltd and Techna Group S.r.l.