The interaction mechanisms between dislocations and nano-precipitates in CuFe alloys: A molecular dynamic simulation

Molecular dynamics (MD) simulations are employed to study the interaction mechanisms between dislocations and nano-precipitates in CuFe alloys. On one hand, the critical shear stress to activate nucleation of dislocations around α-Fe nano-precipitates is substantially reduced, which promotes twinning deformation and dislocation gliding away from the nano-precipitates. On the other hand, nano-precipitates could also prevent dislocations from moving towards themselves. A hybrid model is developed to demonstrate the strengthening behaviors with an enhancing efficiency factor (β) introduced. Large α-Fe nano-precipitates lead to high strengthening efficiency, but an optimized size is obtained owing to the softening effect of large nano-precipitates. Moreover, the strengthening effects of nano-precipitates will disappear if the loading speed exceeds a critical value.