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Temperature Dependence of Grain Boundary Migration in 3-D Hao Zhang David J. Srolovitz

Temperature Dependence of Grain Boundary Migration in 3-D Hao Zhang David J. Srolovitz Princeton University Princeton Materials Institute (PMI). Acknowledgements Moneesh Upmanyu ORNL

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Temperature Dependence of Grain Boundary Migration in 3-D Hao Zhang David J. Srolovitz

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  1. Temperature Dependence of Grain Boundary Migration in 3-D Hao Zhang David J. Srolovitz Princeton University Princeton Materials Institute (PMI) Acknowledgements Moneesh Upmanyu ORNL Lasar Shvindlerman Russian Academy of Sciences/RWTH Gunther Gottstein RWTH Aachen S. Srinivasan LANL

  2. Outline • Atomic Simulation Model • Modeling Approach • Driving Force Dependence of Migration • Recent 3-D Results (Temperature Dependence) • Reduced Mobility • Grain Boundary Energy • Mobility • Activation Energy • Conclusions

  3. Grain Boundary Migration • Grain boundary migration • Absolute reaction rate theory(Turnbull, 1951) • Grain growth (capillarity-induced migration)

  4. v(y) Modeling Approach • U-shaped half loop geometry • FCC Aluminium <111> Tilt Grain Boundary • EAM – Al • Periodic along X, Y and Z • Local velocity • Steady-state velocity • Boundary energy

  5. Reduced Mobility Mgbggb (ao/t) Migration rate v (ro/t) Grain Boundary Energy (J/m2) Driving Force k=p/w (nm-1) Driving Force Dependence of Migration • For sufficiently low driving forces : • Reduced mobility is independent of driving force (2-D) • Migration rate is proportional to driving force (2-D) • Grain Boundary Energy is large (3-D)

  6. Grain Boundary Migration S7 Grain Boundary at T=427K

  7. S13 S7 M* vs. Misorientation (m4/Js) (deg)

  8. S13 S13 S7 S7 Mobility and γ vs. Misorientation (J/m2) (m4/Js) (deg) (deg)

  9. S13 S7 Mobility vs. Misorientation (m4/Js) (deg)

  10. Simulation Experiments Temperature Dependence of Mobility

  11. Simulation S13 S7 S7 Q (eV) Misorientationq(deg) Activation Energy vs. Misorientation experiment (eV) (deg)

  12. Conclusions • Reduced mobility shows local maxima at low S7 • Mobility shows maxima at low S misorientations • Boundary energy exhibits minima at low Smisorientations • Magnitude of activation energy in simulation << than in experiment • Possible reasons: simulations do not represent the true physics impurities

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