Elastic and thermal properties of selected 211 MAX phases: A DFT study

Abstract

MAX phases are a class of ternary materials that have continued to play a key role in the field of materials science due to their unique properties that bridge the gap between metals and ceramics. However, there still remains a need to understand, particularly when the materials are used in harsh environments of say, elevated temperatures. This study sought to address some of these challenges, by determining the elastic and thermal properties of seven MAX-phase materials, namely, Ti2AlC, Ti2AlN, Ti2GaC, Ti2GaN, Ti2PbC, Ti2CdC and Ti2SnC using the density functional theory codes. The calculated values of the melting temperatures ranged from 1100 to 1700 K and hence indicate that the considered 211 MAX phase series are good candidates for high-temperature applications. Thermoelastic profiles obtained, under varying temperature and pressure conditions, show volume reduction with increasing pressure, for Ti2AlC and Ti2CdC, considered as being representative of the series under study. The temperature-dependent lattice thermal conductivity, κph, of the seven MAX phases, was also estimated from Slack's equation, revealing that Ti2AlN has the highest value while Ti2PbC has the lowest value at all the temperatures investigated.