First Principles Study of Bonding Mechanisms at the TiAl/TiO2 Interface

Alexander V Bakulin,Stephen Hocker,Svetlana E Kulkova,Siegfried Schmauder,Sergey S Kulkov

doi:10.3390/met10101298

Abstract

The adhesion properties of the TiAl/TiO2 interface are estimated in dependence on interfacial layer composition and contact configuration using the projector augmented wave method. It is shown that a higher value of the work of separation is obtained at the interface between the Ti-terminated TiAl(110) surface and the TiO2(110)O one than at that with the Al-terminated alloy. An analysis of structural and electronic factors dominating the chemical bonding at the interfaces is carried out. It is shown that low bond densities are responsible for low adhesion at both considered interfaces, which may affect the spallation of oxide scale from the TiAl matrix.

Highlights

Among the big family of intermetallic compounds, Ti-Al alloys attract much attention from both experimental and theoretical researchers
We focus on the modeling of the TiAl/TiO2 interface and its adhesion properties
The atomic and electronic structure of the TiAl(110)/TiO2 (110) interface was calculated by the projector-augmented wave (PAW) method in the plane-wave basis [31,32], implemented in the Vienna

Summary

Introduction

Among the big family of intermetallic compounds, Ti-Al alloys attract much attention from both experimental and theoretical researchers. Liu et al [16] demonstrated that the occurrence of Al self-segregation at the TiAl(111) surface can enhance the interaction between O and Al atoms and promote the growth of a pure alumina layer It was shown in [17] that alloy doping by Nb increases the diffusion barrier of oxygen and can improve the oxidation resistance. TiAl(110)Al /TiO2 (110)O interface, and Nb makes the oxygen atoms detach from TiO2 and primarily bond with the Al atomic layer in the TiAl surface The latter can improve the oxidation resistance of γ-TiAl. In other work [29], the strength of the O–Al and O–Ti bonds were compared at the TiAl/Al2 O3 interface. We focus on the modeling of the TiAl/TiO2 interface and its adhesion properties

Computational Details

Surface Energy

Work of Separation

Atomic and Electronic Factors

Conclusions