Compressive deformation mechanism of equiatomic nickel copper alloy with faceted grain boundary: molecular dynamics simulations
摘要
The presence of grain boundaries in a configuration is known to alter the mechanical properties of a material. In the present investigation, the authors have incorporated a Σ3 [111] 60° {11 8 5}/(8 11 5) grain boundary in an equiatomic nickel–copper alloy. The mechanical behavior of this bicrystalline configuration was studied under uniaxial compression using the molecular dynamics simulation. This classical mechanics-based simulation was carried out at a temperature of 300 K and at a strain rate of 109 s−1. From the result point of view, it was revealed that the incipient plasticity was accompanied by the emergence and subsequent propagation of the Shockley partial dislocations from the tips of the incoherent twin boundaries. This propagation led to the formation of the stacking faults. Interestingly, beyond the yield point, the configuration exhibited significant strain hardening, which is due to the strengthening effect arising from the presence of the stacking faults. The migration of the dislocations (specifically, Shockley partial dislocations) was also observed during this phase. Further compressive deformation led to the material softening. This is attributed to the dislocations’ migration through the cross-slip plane, which interact with stacking faults and the grain boundary, leading to their disintegration. Finally, the presence of a high percentage of solute atoms restricted the grain boundary migration due to the combined solute drag and the solute pinning effects.