Mechanical response to axial strain in AuPd nanowires

The response of metal nanowires to external mechanical loads is a central issue for the design of devices where nanowires play an active role; this response may depend not only on the composition and thickness of the nanowire, but also on the crystallographic orientation of the nanowire with respect to its main axis. In this study, we performed a set of molecular dynamics simulations of tensile tests in a displacement-controlled environment of AuPd nanowires of several diameters and compositions, grown in the [ 100 ] , [ 110 ] , and [ 111 ] directions. We found that the [ 100 ] nanowires have a Young’s modulus about 60 GPa lower than that of the [ 111 ] nanowires, with the [ 110 ] nanowires showing intermediate values. Moreover, the [ 100 ] nanowires exhibit the highest tensile strength. In the plastic regime, the nucleation of highly mobile Shockley dislocations creates stacking faults, and, less frequently, nanotwins. The displacement of the dislocations provokes abrupt drops in the stress–strain curve, but, when a stacking fault crosses another, stress accumulates, in particular in [ 110 ] nanowires, where hardening is common, mainly due to the presence of stair-rod dislocations.