EBSD and TKD analyses using inverted contrast Kikuchi diffraction patterns and alternative measurement geometries

Area of Science:

• Materials Science
• Crystallography
• Electron Microscopy

Background:

• Electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD) patterns can exhibit inverted Kikuchi band contrast.
• This phenomenon occurs due to anomalous absorption, particularly in samples with nanoscale topography, low-tilt geometries, or thicker specimens in TKD.

Purpose of the Study:

• To demonstrate the application of physics-based simulated master patterns with inverted contrast for accurate crystal orientation determination.
• To address challenges in indexing EBSD and TKD patterns where standard methods fail due to contrast inversion.

Main Methods:

• Utilized physics-based simulated master patterns with inverted contrast for indexing.
• Applied brute force indexing for complex cases.
• Investigated EBSD on gold nanostructures and non-tilted surfaces.
• Examined TKD on duplex stainless steel foils.
• Mathematically inverted inverted-contrast patterns to normal contrast.

Main Results:

• Successfully indexed previously uninterpretable EBSD patterns from gold nanostructures using contrast-inverted master patterns.
• Indexed EBSD maps from a non-tilted surface by applying contrast-inverted patterns.
• Indexed significant areas of thicker TKD samples exhibiting contrast inversion, expanding evaluable data.
• Achieved successful Hough/Radon-based indexing after mathematically inverting contrast-inverted patterns.

Conclusions:

• Physics-based simulated master patterns with inverted contrast are effective for solving crystal orientation problems.
• This approach significantly enhances the success rate and area coverage in EBSD and TKD analyses, especially for challenging sample geometries and conditions.