Insights into the interfacial bonding strength of TiB/Ti: A first principles study

Abstract

First-principles calculations are performed to study the strength and nature of interfacial bonding at TiB/Ti interfaces. Sixteen (100)TiB/(101¯0)α-Ti interface models considering different (100)TiB terminations and stacking sites are investigated to determine their influence on the interfacial bonding strength and thermodynamic stability. The L bridge-site-B1-termination interface exhibits the strongest interfacial bonding and the most stable structure, forming strong Ti–B polar covalent bonds and maintaining the same epitaxial stacking sequence as bulk TiB at the interface. Moreover, seven alloying elements commonly used in titanium alloys are investigated to tailor the interfacial bonding strength of TiB/Ti interfaces. The calculated results indicate that the alloying elements of V, Cr, and Mo form stronger chemical bonds with B atoms than with Ti and have the tendency to aggregate at the TiB/Ti interface region, while improving its interfacial bonding strength. The alloying elements of Al, Si, Zr, and Sn generate weaker chemical bonds with B atoms and preferentially aggregate at sites away from the TiB/Ti interface. This tends to maintain or even lower the interfacial bonding strength of the interface. The calculated results, especially for V, are in good agreement with previous experimental observations. It is believed that the calculated results can provide theoretical evidence to guide experimental designs and improve the interfacial and macromechanical properties of TiB-reinforced titanium matrix composites.