Theoretical study on surface stability, distortion and oxygen adsorption behavior of TiZrHfNb high entropy alloys

First principles and Monte Carlo methods are performance to study the effects of component distribution and distortion on the surface stability of TiZrHfNb (100), (110) and (111). It is found that the (100) surface is more stable than the others. The element Zr enrichment is obvious on the (100), which is beneficial to improve the surface stability of (100). In this research, the relationships between d-band center, work function and surface stability of (100) surface model are studied. In addition, the bonding interactions of (100) surface configuration are analyzed by means of density of states and charge difference distributions. Bader charge is also used to reveal the relationship between the interaction of elements and the surface stability. The local lattice distortions greatly affect the surface stability especially the Ti element. Further, the adsorption characteristics of oxygen atoms on TiZrHfNb surfaces with different atomic arrangements may be different because of the differences between d-band center values of the surfaces. The bonding between component elements can increase the activity of d-orbital electrons, which is helpful to the interaction between metal atoms and oxygen during oxidation, thus changing the oxidation properties of alloys.