Configurational Thermodynamics Of A 1/2111 Screw Dislocation Core In Mo-W Solid Solutions Using Cluster Expansion

In this work, we have developed a methodology to obtain an ab initio cluster expansion of a system containing a dislocation and studied the effect of configurational disorder on the 1/2111 screw dislocation core structure in disordered Mo1-xWx alloys. Dislocation cores control the selection of glide planes, cross slip, and dislocation nucleation. Configurational disorders in alloys can impact the dislocation core structure and affect dislocation mobility. For our calculations, we have used a quadrupolar periodic array of screw dislocation dipoles and obtained the relaxed structures and energies using density functional theory. We have obtained the dislocation core structure as a function of composition and the interaction energies of solutes with the dislocation as a function of position with respect to the core. With these energies, we performed mean-field calculations to assess segregation toward the core. Finally, with the calculated energies of 1848 alloy configurations with different compositions, we performed a first principle cluster expansion of the configurational energetics of Mo1-xWx solid solutions containing dislocations.