Deformation twinning in Au30Ag70 alloy nanowires under tensile strain

Abstract

Defect-free AuAg alloy nanowires have the potential to be used in various plasmonic devices due to their superior chemical stability and broad applicable range of wavelengths. Alloyed nanowires have different stacking fault energies that can result in different deformation behavior compared to single element nanowires; however, an in-depth analysis of such material system is yet to be explored. In this study, defect-free single crystalline Au30Ag70 alloy nanowires are synthesized by topotaxial growth method and tested in tension using an in-situ pico-indenter. Deformation twinning that results in superplastic deformation of alloy nanowires is experimentally observed. The critical dimension of Au30Ag70 alloy nanowires at which transition from ordinary plasticity to deformation twinning occurs, is experimentally determined to be ∼333 nm, which is about 2 time larger than that of Au nanowires. Stacking fault energy, which is the key element determining the deformation mode, of Au30Ag70 alloy nanowires is 21 mJ/m2, which is smaller than that of Au nanowire with stacking fault energy of 31 mJ/m2. The decrease in the stacking fault energy in the case of the alloy nanowires resulted in stabilization of deformation twinning to a larger critical dimension before transitioning to ordinary plasticity.