We study experimentally the intermittent progress of the mechanically induced
martensitic transformation in a Cu-Al-Be single crystal through a full-field
measurement technique: the grid method. We utilize an in- house, specially
designed gravity-based device, wherein a system controlled by water pumps
applies a perfectly monotonic uniaxial load through very small force
increments. The sample exhibits hysteretic superelastic behavior during the
forward and reverse cubic-monoclinic transformation, produced by the evolution
of the strain field of the phase microstructures. The in-plane linear strain
components are measured on the sample surface during the loading cycle, and we
characterize the strain intermittency in a number of ways, showing the
emergence of power-law behavior for the strain avalanching over almost six
decades of magnitude. We also describe the nonstationarity and the asymmetry
observed in the forward versus reverse transformation. The present experimental
approach, which allows for the monitoring of the reversible martensitic
transformation both locally and globally in the crystal, proves useful and
enhances our capabilities in the analysis and possible control of
transition-related phenomena in shape-memory alloys.Comment: Four supplementary video
