Nanoindentation based investigations of PLC-type plastic instability

Nanoindentation based investigations of PLC-type plastic instability

  • Date: Apr 11, 2019
  • Time: 04:00 PM - 05:00 PM (Local Time Germany)
  • Speaker: Dr. Henry Ovri
  • Helmholtz Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Geesthacht, Germany
  • Location: Max-Planck-Institut für Eisenforschung GmbH
  • Room: Large Conference Room No. 203
  • Host: Prof. Gerhard Dehm / Dr. Christoph Kirchlechner
Portevin Le-Chatelier (PLC) effect is a type of plastic instability that results in severe strain localization, reduction in ductility and formation of surface striations during forming operations. Understanding the underlying microscopic mechanism(s) that govern it requires detailed experimental investigations of the relationships between the phenomenon and local microstructural constituents. Most current models of PLC, both phenomenological and theoretical, are based on descriptions of mesoscopic observations and global responses observed in stress-strain curves. More predictive (or physically based) models will require investigations at the microstructural length-scales. In this talk, it will be shown that the gap in understanding of the microscopic origins and macroscopic manifestations of PLC can be bridged by nanoindentation testing. Specifically, it will be shown that by exploiting the high resolution of force and displacement measurements and the site-specific capabilities of the nanoindenter, coupled with complimentary microstructural characterization techniques, we are able to gain new insight into critical aspects of the PLC effect, including its anisotropy, underlying governing mechanisms and associated activation parameters.
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