New insight into the structural, mechanical, electronic, and thermodynamic properties of the monoclinic<scp>TMAl₃</scp>‐type aluminides

Abstract

Abstract Despite of the potential high‐temperature technological applications of MoAl 3 alloy because of high‐temperature strength and good oxidation resistance, the structure and related properties of the monoclinic TMAl 3 aluminides are entirely unclear. Here, we apply the first‐principles calculation to study the structure, elastic, electronic, and thermodynamic properties of the monoclinic TMAl 3 . Five novel monoclinic TMAl 3 aluminides: ScAl 3 , TiAl 3 , VAl 3 , CrAl 3 , and WAl 3 are first predicted. The result shows that the hardness of the monoclinic TiAl 3 is 13.0 GPa, which is larger than the tetragonal TiAl 3 . In particular, the calculated elastic modulus and hardness of WAl 3 are larger than the other TMAl 3 because of the heavy valence electronic density of metal W. Importantly, it is first found that the monoclinic MoAl 3 shows the semiconductor properties with the band gap of 0.047 eV. In addition, the calculated Debye temperature of the monoclinic CrAl 3 is 537.6 K, which is larger than the other monoclinic TMAl 3 . Essentially, the thermal stability of the monoclinic TMAl 3 relies on the vibration of Al and AlAl bond.

Topics & Concepts