Processing and characterization of new Ti3AlC2-yNy MAX solid solutions

Replacement of C by N in Ti3AlC2 to form Ti3AlC2-yNy (y<2) MAX solid solutions has attracted much attention due to their tailored mechanical, thermal, and chemical properties. So far, only Ti3AlCN, as y = 1 for Ti3AlC2-yNy, has been successfully synthesized, exhibiting improved properties as compared with Ti3AlC2. Theoretical work predicts that Ti3AlC2-yNy solid solutions become more metallic and conductive as more N atoms substitute C atoms. However, there is no report on the successful synthesis of Ti3AlC2-yNy with a wide range of y values. Here we report on the synthesis of Ti3AlC2-yNy sold solutions by a facile pressureless-sintering technique. Influencing factors such as starting mixture, sintering temperature, and Al addition on the formation of Ti3AlC2-yNy have been investigated. The experimental results showed that Ti3AlC2-yNy (y = 0.3, 0.5, 1.0, 1.1, and 1.2) solid solution phases can be achieved in the temperature range from 1430 to 1500 °C. The phase composition and microstructure of the resultant phases were characterized. The achieved Ti3AlC2-yNy phases expand the category of MAX solid solutions, and they are the preferred precursors for preparing two dimensional carbonitride Ti3C2-yNyTx MXene.