Tailoring the hydrogenated mechanism of Pt3Al from first-principles investigation

Pt–Al compounds are promising high-temperature structural materials. However, the hydrogenated behavior of Pt3Al is still unclear. To explore the hydrogenated mechanism, we apply the first-principles method to investigate the role of hydrogen (H) in Pt3Al. Here, the cubic and tetragonal Pt3Al are considered. Based on the hydrogen occupied position, three H-doped sites are designed in cubic and tetragonal phases. It is found that the hydrogen is a thermodynamic stability in two Pt3Al phases. Compared to the cubic Pt3Al, the hydrogen prefers to occupy the octahedral interstice (H(2) site) of the tetragonal Pt3Al. Importantly, the H-doped Pt3Al is a mechanical stability. In particular, it is found that the hydrogen weakens the volume deformation resistance, shear deformation resistance and elastic stiffness of Pt3Al. But the hydrogen improves the ductility of Pt3Al due to the electronic interaction between hydrogen and Pt3Al. Naturally, the low elastic properties are that the introduction of hydrogen weakens the localized hybridization between Pt atom and Al atom, and forms the H–Pt bond. In addition, the hydrogen also weakens the Debye temperature (θD) of Pt3Al.