Elastic Properties of Co/Cu Nanocomposite Nanowires

Abstract

The mechanical deformation of Co/Cu composite nanowires was simulated by molecular dynamics in a state of uniaxial tensile and compressive stress. The Young’s modulus and initial yield stress have been derived from the stress–strain curves at different conditions. For tensile strength, the effect of strain rate, volume/surface area ratio, temperature, and thickness ratio between Co and Cu sublayers was analyzed depending on the crystallographic orientations of the nanowires. At high values, the elastic modulus and yield stress depend on the strain rate; and some differences with the crystallographic orientation due to nonlinear effects appear. Both magnitudes diverge from the bulk values with decreasing the volume/surface area ratio, increasing in the case of 〈110〉 nanowires and decreasing for the other two directions. For 〈100〉 nanowires, grains undergo a crystallographic reorientation towards 〈111〉 and 〈110〉 directions. Besides, for these nanowires hexagonal close-packed atoms are preferably in the Co sublayer; and face-centered cubic atoms, in the Cu sublayer unlike nanowires in the other two directions. Plastic deformation takes place more easily in Cu sublayers. Nanowires show differences in the slip mechanism for 〈110〉 and 〈100〉 directions. In compression, the former system slips via both {111}〈112〉 and {111}〈110〉 dislocations; and the latter, only through {111}〈112〉 dislocations.