Atomistic modeling of defect-induced plasticity in CuNb nanocomposites

E Martinez and A Caro and IJ Beyerlein, PHYSICAL REVIEW B, 90, 054103 (2014).

DOI: 10.1103/PhysRevB.90.054103

CuNb nanocomposites have proven stable under light-ion irradiation, although their response to heavy-ion bombardment and subsequent loading is still uncertain. In this paper we analyze the change in mechanical properties of model CuNb nanocomposites in vacancy supersaturated environments, mimicking certain effects introduced by heavy-ion irradiation. We have performed compression tests using molecular dynamics for different defect contents. The presence of defects substantially modifies the system response upon external loading. The dislocation nucleation mechanism changes with the interface atomic density. Stacking fault tetrahedra in the Cu layer may act as dislocation sources to lower significantly the yield stress and the same applies for voids present in the Nb layer. We have analyzed in detail the dislocation-interface interaction mechanisms under different conditions, showing how dislocations react with the misfit dislocations present at the interface to modify the atomic structure of the boundary, which suggests that the interface could be designed to optimize its defect healing properties. We conclude that heavy-ion irradiation softens the multilayer nanocomposites and that interfaces help in recovering these materials as they absorb the dislocations created from irradiation-induced defects.

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