Investigating the electronic origins of the repulsion between substitutional and interstitial solutes in hcp Ti

The high solubility of oxygen in Ti, Zr, and Hf makes it difficult to stabilize protective oxide scales on their surfaces as the subsurface regions can serve boundless sinks that continuously dissolve oxygen. Alloying elements are crucial reduce diffusivity within early transition metals. Past studies have shown most substitutional alloying additions titanium repel interstitial Here we use first-principles calculations show this repulsion is short ranged explore several factors likely responsible for repulsive interaction. Calculations Bader charges suggest existence short-range Coulomb interactions due accumulation charge solute drawn from Ti host. Misfit strains differences atomic radii solutes also found play a role. We identify unique hybridization phenomenon between dissolved hcp leads interaction at distances, similar closed-shell atoms, which especially pronounced Al Si solutes.