Yield strength asymmetry in metal nanowires

We performed atomistic simulations to study the yield mechanisms in gold nanowires. Perfect fcc gold nanowires all yield via the nucleation and propagation of {111}<112> partial dislocations. The magnitude of the yield stress is much larger in tension versus compression for very small <100> nanowires, and this asymmetry is primarily due to the effects of surface stresses and different slip systems active during tensile and compressive yielding. Nanowires with a <111> orientation only show significant tension-compression asymmetry when defects exist in the wire prior to reverse compressive loading.