Effect of twin boundary spacing on the mechanical properties of nano-columnar crystalline Cu-Ni alloy

ABSTRACTNanotwinned exist in crystals as coherent interfaces with low interfacial energy, which can not only improve the strength of metal materials, but also increase the ductility. In this manuscript, we have performed molecular dynamics simulations of the mechanical properties of a nano-columnar crystalline Cu-Ni alloy with different twin boundary spacing. It is found that the model without twin has a stacking fault tetrahedron composed of stair-rod dislocations, which results in a small change in dislocation density at the later stage of deformation, and the average stress after yielding is lower than that of the model with twin. During the deformation process, with the increase of Other atoms, the dislocation slip barrier is enhanced, the tensile strength is increased, and the yield phenomenon is delayed, which is more obvious with the decrease of twin boundary spacing. The dislocation density decreases with the decrease of the spacing of the twin boundary, and the dislocation segments become shorter. When the twin boundary spacing is 0.625 nm, the tensile strength is increased by about 71% compared with the model without twin structure.KEYWORDS: Nanotwinnedmechanical propertiesmolecular dynamicsCu-Ni alloy Disclosure statementThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.Additional informationFundingThe work was supported by Local Science and Technology Development Fund Projects Guided by the Central Government of China (grant number 23ZYQB300), the National Key R&D Program of China (grant numbers 2017YFA0700701, 2017YFA0700703), National Natural Science Foundation of China (grant number 52061025), Key Research Program of Education Department of Gansu Province (grant number GSSYLXM-03).