Effects of Al substitution by Si in Ti3AlC2 nanolaminate

Recently, a series of high-purity Ti 3 (Al 1− x Si x )C 2 solid solutions with new compositions ( x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been reported with interesting mechanical properties. Here, we have employed density functional theory for Ti 3 (Al 1− x Si x )C 2 solid solutions to calculate a wider range of physical properties including structural, electronic, mechanical, thermal and optical. With the increase of x , a decrease of cell parameters is observed. All elastic constants and moduli increase with x . The Fermi level gradually increases, moving towards and past the upper bound of the pseudogap, when the value of x goes from zero to unity, indicating that the structural stability reduces gradually when the amount of Si increases within the Ti 3 (Al 1− x Si x )C 2 system. In view of Cauchy pressure, Pugh’s ratio and Poisson’s ratio all compositions of Ti 3 (Al 1− x Si x )C 2 are brittle in nature. Comparatively, low Debye temperature, lattice thermal conductivity and minimum thermal conductivity of Ti 3 AlC 2 favor it to be a thermal barrier coating material. High melting temperatures implies that the solid solutions Ti 3 (Al 1− x Si x )C 2 may have potential applications in harsh environments. In the visible region (1.8–3.1 eV), the minimum reflectivity of all compositions for both polarizations is above 45%, which makes them potential coating materials for solar heating reduction.