Plasticity of indium nanostructures as revealed by synchrotron X-ray microdiffraction

Indium columnar structures with diameters near 1 mu m were deformed by uniaxial compression at strain rates of approximately 0.01 and 0.001 s(-1). Defect density evolution in the nanopillars was evaluated by applying synchrotron Laue X-ray microdiffraction (mu SLXRD) on the same specimens before and after deformation. Results of the mu SLXRD measurements indicate that the dislocation density increases as a result of mechanical deformation and is a strong function of strain rate. These results suggest that the rate of defect generation during the compression tests exceeds the rate of defect annihilation, implying that plasticity in these indium nanostructures commences via dislocation multiplication rather than nucleation processes. This is in contrast with the behaviors of other materials at the nanoscale, such as, gold, tin, molybdenum, and bismuth. A hypothesis based on the dislocation mean-free-path prior to the multiplication process is proposed to explain this variance. (C) 2012 Elsevier B.V. All rights reserved.