Phase stability, elastic, electronic, thermal and optical properties of Ti _3Al _(1-x)Si _xC _2 (0≤x≤1): First principle study

摘要

The structural parameters with stability upon Si incorporation and elastic, electronic, thermodynamic and optical properties of Ti _3Al _(1-x)Si _xC _2 (0≤x≤1) are investigated systematically by the plane wave pseudopotential method based on the density functional theory (DFT). The increase of some elastic parameters with increasing Si-content renders the alloys to possess higher compressive and tensile strength. The Vickers hardness value obtained with the help of Mulliken population analysis increases as x is increased from 0 to 1. The solid solutions considered are all metallic with valence and conduction bands, which have a mainly Ti 3d character, crossing the Fermi level. The temperature and pressure dependences of bulk modulus, normalized volume, specific heats, thermal expansion coefficient, and Debye temperature are all obtained through the quasi-harmonic Debye model with phononic effects for T=0-1000 K and P=0-50 GPa. The obtained results are compared with other results available. Further an analysis of optical functions for two polarization vectors reveals that the reflectivity is high in the visible-ultraviolet region up to ～10.5 eV region showing promise as a good coating material.