Estimations of bulk geometrically necessary dislocation density using high resolution EBSD

Area of Science:

• Materials Science
• Crystallography
• Solid Mechanics

Background:

• Geometrically necessary dislocations (GNDs) are critical for understanding material plasticity.
• Electron backscatter diffraction (EBSD) is a standard technique for estimating GNDs via lattice orientation.
• Accurate characterization of GNDs is essential for predicting material behavior.

Purpose of the Study:

• To present a complementary method for estimating bulk GND density.
• To utilize local lattice curvature and strain gradients from HR-EBSD for GND assessment.
• To validate approximations of GND content through simulations.

Main Methods:

• Employing high-resolution electron backscatter diffraction (HR-EBSD) to measure local lattice curvature and strain gradients.
• Developing a continuum adaptation of classical dislocation distortion equations.
• Simulating random GND fields to validate estimation methods.

Main Results:

• A novel approach to estimate bulk GND density using HR-EBSD derived lattice curvature and strain gradients.
• Validation of various approximations for GND content through simulated GND fields.
• Demonstration of HR-EBSD as a powerful tool for GND characterization.

Conclusions:

• HR-EBSD offers a complementary and potentially more accurate method for quantifying GNDs.
• The developed continuum model aids in understanding and validating GND density estimations.
• This work advances the characterization of microstructural features influencing material plasticity.