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Gregory Sparks1 Robert Maass1

1, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States

It has been well established that plastic deformation of microcrystals proceeds intermittently in time, with this behavior generally attributed to sudden, collective dislocation rearrangements (dislocation avalanches). However, previously it was not possible to access the temporal sub-structure of these intermittent slip events. In this talk, we discuss use of the recently validated high-data-acquisition-rate nanoindentation technique to investigate the evolution of slip velocity during intermittent slip events in metallic microcrystals from two different crystal systems, namely FCC (represented by Au) and BCC (represented by Nb). We will discuss the (previously demonstrated) similarity of the event-size distributions between the two systems in order to contrast this with the notable differences observed in event velocities and mean profile shape. In particular, we will focus on the dramatically extended velocity relaxation for slip events in the Nb samples relative to the Au samples.

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