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Deformation Twinning in FCC materials

Jaswanth Bommidi
Department of Materials Science & Engineering, University of Tennessee

This page shows visualizations of the sigma 9 GB with 19.47 degree misorientation angle deformed at 1E-3 strain rate

Twinning is one of the primary deformation mechanisms by which materials deform. Slip being the more pronounced deformation at normal conditions and twinning requiring large movement of atoms at once, examination of the conditions at which twinning occurs is performed for FCC materials. A source of partials is required to create stacking faults that eventually result in the formation of twins. sigma 3 and sigma 9 Grain Boundaries (GBs) for Al are uniaxially deformed at different strain rates to create the partials and interactions are investigated. The previous research has shown that sigma 9 GBs has resulted in formation of twins at 77K. The present research work is being performed to see how different GBs deform under the same conditions of tensile deformation as sigma 9 GBs. The same sigma 9 GBs of Al alloy will be deformed at 100K and 200K at 1E-3 and 1E-2 strain rates using NPT ensemble in y-direction perpendicular to the GB. Before the deformation the material will be relaxed to the particular deformation temperature for 25 ps with a timestep of 1fs. During deformation, a strain rate of 1E-3 for 0.2 ns and 1E-2 for 20ps is applied. Similar conditions is applied for sigma 3 GB with same misorientation angle as sigma 9 GB to see how the mismatch at GB causes change in the deformation mechanisms.1

Interactive Structures

Color Legend:

  • blue = FCC
  • green = HCP
  • red = non-cubic


M.I. Mendelev, M.J. Kramer, C.A. Becker, and M. Asta (2008), "Phil Mag., 88(12), 1723- 1750, doi: 10.1080/14786430802206482

posted: April 2020.
updated: April 2020.