Quantifying the solute-induced additional repulsive force between two partials of pure screw dislocations

The interactions between two partials of a pure screw dislocation are closely associated with numerous deformation mechanisms in face-centered cubic metals. However, the classical method for quantifying the repulsive force between two partials fails for some binary alloys or the newly emerging medium/high entropy alloys due to the presence of additional forces arising from the randomly distributed solute atoms. This paper presents a study on the interaction between two curved partial dislocations, taking into account the effects of solute-induced dislocation perturbations through the use of elastic mechanics and atomistic simulations. The theoretical analysis reveals the existence of an additional repulsive force between two curved partials, which monotonically increases with the average power spectrum of perturbation amplitudes, i.e., Δ f ∝ ⟨ ( C n ) 2 ⟩ . Atomistic simulations of CuAg and CuTa alloys further demonstrate that the average power spectrum exhibits a linear dependence on the solute fractions, denoted as ⟨ ( C n ) 2 ⟩ ∝ χ , which bears resemblance to the relationship between power spectrum and temperature, i.e., ⟨ ( C n ) 2 ⟩ ∝ T in the case of temperature-induced fluctuations. Therefore, it can be concluded that the additional repulsive force is linearly proportional to the solute fractions in binary alloys. The methodology presented in this study can be easily applied to other face-centered cubic (FCC) alloys as well as multicomponent solute-strengthened alloys.