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Motivated by the recent experimental reports, we explore the formation of Rayleigh-like instability in metallic nanowires during the solid state annealing, a concept originally introduced for liquid columns. Our molecular dynamics study using realistic interatomic potential reveals instability induced pattern formation at temperatures even below the melting temperature of the wire, in accordance with the experimental observations. We find that this is driven by the surface diffusion, which causes plastic slips in the system initiating necking in the nanowire. We further find the surface dominated mass-transport is of subdiffusive nature with time exponent less than unity. Our study provides an atomistic perspective of the instability formation in nanostructured solid phase.

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Dislocation pinning plays a vital role in the plastic behaviour of a crystalline solid. Here we report the first observation of the damped oscillations of a mobile dislocation after it gets pinned at an obstacle in the presence of a constant static shear load. These oscillations are found to be inertial, instead of forced as obtained in the studies of internal friction of solid. The rate of damping enables us to determine the effective mass of the dislocation. Nevertheless, the observed relation between the oscillation frequency and the link length is found to be anomalous, when compared with the theoretical results in the framework of Koehler's vibrating string model. We assign this anomaly to the improper boundary conditions employed in the treatment. Finally, we propose that the inertial oscillations may offer a plausible explanation of the electromagnetic emissions during material deformation and seismic activities.