Influence of vacancy on the mechanical and thermodynamic properties of PtAl2 from the first-principles investigation

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ABSTRACT The point defect plays an important role in high-temperature materials. Although PtAl2 is a promising high-temperature alloy, the mechanism of point defect in PtAl2 is entirely unknown. By using the first-principles calculations, here, we study the influence of vacancy on the structural stability, mechanical and thermodynamic properties of PtAl2. Two vacancy types – Al vacancy and Pt vacancy – are considered. The calculated result shows that PtAl2 prefers to form the Al vacancy in comparison to the Pt vacancy. The calculated elastic modulus of Al vacancy is larger than the Pt vacancy. Essentially, the low elastic modulus is that the removed atom changes the localised hybridisation between Pt and Al. PtAl2 with these vacancies also shows ductility behaviour. Finally, it is found that the calculated Debye temperature of Al vacancy is lower than the perfect PtAl2. However, the calculated Debye temperature of Pt vacancy is higher than the perfect PtAl2. Therefore, this work theoretical reveals the vacancy mechanism of PtAl2 alloy and provides a new path to improve the mechanical and thermodynamic properties of PtAl2 high-temperature alloy.