Cr concentration driving the structural, mechanical, and thermodynamic properties of Cr‐Al compounds from first‐principles calculations

Cr‐Al binary compounds are regarded as the potential high‐temperature structural materials. However, the structure and important properties of Cr‐Al compounds are not completely unclear. Here, we report on the influence of Cr concentration on the structural, mechanical, and thermodynamic properties of Cr‐Al compounds by using the first‐principles calculations. Four novel Cr‐Al compounds, Cr3Al8 with monoclinic structure (C2/m), Cr3Al5 with hexagonal structure (P63mc), Cr2Al3 with tetragonal structure (I4/mmm), and Cr3Al with cubic structure (Pm‐3 m), are predicted. The calculated elastic modulus of Cr‐Al compounds gradually increases with increasing Cr concentration. Compared to other Cr‐Al compounds, our predicted Cr3Al with cubic structure exhibits a strong deformation resistance and high hardness due to symmetrical CrAl bonds. However, the Debye temperature of Cr7Al3 is larger than that of other Cr‐Al compounds. The calculated phonon density of state shows that the high‐temperature thermodynamic properties of Cr‐Al compounds are attributed to the vibration of Al atom and CrAl bond.