Strain bursts in plastically deforming Molybdenum micro- and nanopillars

TL;DR

This study statistically analyzes strain bursts during plastic deformation of monocrystalline molybdenum micropillars, revealing power-law and Weibull distributions in deformation events and stress increments, independent of orientation or stress rate.

Contribution

It provides a detailed statistical characterization of strain bursts in molybdenum micro- and nanopillars, highlighting universal distribution patterns across different conditions.

Findings

Strain burst sizes and rates follow power-law distributions.

Stress increments between bursts are Weibull distributed with size effects.

Distributions are independent of specimen orientation and stress rate.

Abstract

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-centered cubic and hexagonal metals.