Prediction of double transition metal (<scp>Cr_1−<i>x</i>Zr_<i>x</i></scp>)<scp>₂AlC MAX</scp> phases as thermal barrier coatings: Insight from density functional theory

Abstract

Abstract Herein, a high purity (Cr 1− x Zr x ) 2 AlC solid solutions (with x = 0–1) have been investigated intensively using the first principles density functional theory calculations. The optimized structural parameters were founded to be in good agreement with the experimental results, and increased steadily with rising Zr in (Cr 1− x Zr x ) 2 AlC solid solutions. The elastic constants C ij and enthalpy formation have been calculated and firmly confirmed that these solid solutions were mechanically and thermodynamically stable. Moreover, the mechanical properties show that the compounds possess brittle behavior with covalent bonding signified that they are relatively hard compared to other MAX phases. Further, the electronic band structures were studied and found a metallic behavior for all the investigated concentrations. Consequently, all the compositions of solid solutions were identified as promising materials for thermal barrier coating and high temperature structural materials due to the high value of melting temperatures and low minimum thermal conductivity.