EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Solute segregation at grain boundaries has a profound influence on the properties of
polycrystalline materials. Here, we are using first-principles methods, i.e. Density Functional Theory (DFT), to determine the binding energies of solutes to the Σ5{013}<100> grain boundary in a BCC Ti-25at%Mo alloy. Mo is added as an alloying element in the simulations to stabilize the BCC phase using a special quasi-random structure (SQS) for the arrangement of Mo atoms in the simulation domain. Yttrium, zirconium and niobium are considered as the solutes in the simulations. Their binding energies are determined for the sites located in the habit plane of the grain boundary. These sites can have different chemical neighbourhoods in terms of their Ti-Mo composition. Thus, a representative binding energy of each solute is obtained by averaging the binding energies for all these individual next neighbour arrangements. The simulation results indicate strong binding to the grain boundary for the three considered solutes with the magnitude of the binding energy increasing with the size of the solute atom. These trends are similar to those previously obtained for BCC titanium stabilized by applying pressure.