Studying Grain Boundary Strengthening by Dislocation-Based Strain Gradient Crystal Plasticity Coupled with a...

Area of Science:

• Materials Science
• Computational Materials Engineering
• Materials Simulation

Background:

• Integrated Computational Materials Engineering (ICME) aims to accelerate materials development through simulations.
• Predicting microstructural evolution and its impact on mechanical properties is crucial.
• The Phase Field (PF) method is a promising tool for simulating microstructural changes under stimuli like deformation.

Purpose of the Study:

• To investigate the influence of grain size on polycrystal mechanical behavior using a novel computational model.
• To assess the capability of a dislocation-based strain gradient crystal plasticity model within a PF framework.
• To explore size effects in materials at the micron length scale.

Main Methods:

• Developed quasi-2D simulations of plastic deformation in a face-centered cubic system.
• Implemented a finite strain formulation combining dislocation-based strain gradient crystal plasticity with a PF code.
• Applied the model to study polycrystals, considering dislocation storage, annihilation, and initial material state.

Main Results:

• The model successfully captured the Hall-Petch effect, showing the relationship between flow stress and grain size.
• The functional dependence of flow stress on grain size was reproduced without special grain boundary properties.
• Predicted Hall-Petch coefficients were smaller than experimental values, but qualitative agreement was good.

Conclusions:

• Dislocation-based strain gradient crystal plasticity models integrated with PF simulations are effective for studying microstructural evolution and mechanical behavior.
• The model provides valuable insights into size effects and the Hall-Petch relationship in polycrystals.
• Further refinement may be needed to match experimental Hall-Petch coefficients precisely.