Gradient Crystal Plasticity: A Grain Boundary Model for Slip Transmission

Area of Science:

• Materials Science
• Solid Mechanics
• Computational Materials Science

Background:

• Dislocation interactions with grain boundaries (GBs) are crucial for plasticity in fine-grained polycrystals.
• Existing continuum plasticity theories need to incorporate GB mechanisms like slip transmission.
• Understanding these interactions is key to predicting material behavior at the nanoscale.

Purpose of the Study:

• To develop a novel grain boundary (GB) model within gradient polycrystal plasticity.
• To incorporate slip transmission mechanisms at GBs, considering geometric and stress factors.
• To investigate the influence of GBs on size-dependent plasticity.

Main Methods:

• Proposed a new GB model including kinematic relations and slip transmission governing equations.
• Incorporated geometric factors: misorientation, GB orientation, GB defects, and stress state.
• Numerically implemented the model for a bicrystal thin film under plane constrained shear.

Main Results:

• GB parameters, grain size, grain misorientation, and GB orientation significantly impact slip transmission.
• Plastic behaviors in fine-grained polycrystals are strongly influenced by these GB factors.
• Model predictions show qualitative agreement with experimental and discrete dislocation dynamics simulation results.

Conclusions:

• The developed GB model effectively captures the influence of slip transmission on plasticity.
• The findings provide a foundation for more accurate continuum plasticity theories in fine-grained materials.
• This work bridges the gap between atomistic/continuum simulations and experimental observations.