Effect of active Ti element on the bonding characteristic of the Ag(111)/α-Al2O3 (0001) interface by using first principle calculation

The Ti active element is of significant importance in brazing Al2O3 using Ag-based filler metals. In this paper, first-principle calculation was used to study the diffusion and reaction mechanism of Ti element at the Ag/Al2O3 interface. The O-terminated Ag(111)/alpha-Al2O3 (0001) interface was found to be the most stable interface firstly. The energy result shows that Ti atom in bulk Ag prefers to diffuse to the interface. Then the Ti atom would form bonding with O atom at the surface of Al2O3, resulting in the Ti-O compounds layer at the interface. When the Ti coverage is 100% at the interface, the work of adhesion (W-ad) increases to 14.16 J/m(2), which is almost twice of the value for clean interface without Ti atom. The analysis of electron structure shows that Ti and O atoms can form strong ionic bonding at the interface, which is much stronger than the ionic-covalent Ag-O bonding.