Strain bursts in plastically deforming molybdenum micro- and nanopillars

Plastic deformation of micron and sub-micron scale specimens is characterized by
intermittent sequences of large strain bursts (dislocation avalanches) which are
separated by regions of near-elastic loading. In the present investigation we
perform a statistical characterization of strain bursts observed in stress-controlled
compressive deformation of monocrystalline molybdenum micropillars. We
characterize the bursts in terms of the associated elongation increments and
peak deformation rates, and demonstrate that these quantities follow power-law
distributions that do not depend on specimen orientation or stress rate. We also
investigate the statistics of stress increments in between the bursts, which are
found to be Weibull distributed and exhibit a characteristic size effect. We discuss
our findings in view of observations of deformation bursts in other materials,
such as face-centred cubic and hexagonal metals.