Nanometres-resolution Kikuchi patterns from materials science specimens with transmission electron forward scatter...

Area of Science:

• Materials Science
• Crystallography
• Electron Microscopy

Background:

• Electron backscattered diffraction (EBSD) is a common technique for phase identification and orientation mapping.
• Conventional EBSD in scanning electron microscopes has limitations in spatial resolution for nanoscale analysis.

Purpose of the Study:

• To evaluate the capability of transmission electron forward scatter diffraction (TEFSD) for nanoscale phase identification and orientation mapping.
• To determine the minimum detectable particle size and achievable resolution using TEFSD.

Main Methods:

• Utilized a charge-coupled device camera in a scanning electron microscope positioned below a thin specimen.
• Collected and analyzed transmission Kikuchi patterns.
• Acquired simultaneous energy dispersive spectrometer X-ray maps and TEFSD orientation maps.

Main Results:

• TEFSD provides phase identification and orientation mapping at the nanoscale.
• Reliable Kikuchi diffraction patterns were detected from palladium particles as small as 5.6 nm.
• An orientation mapping resolution of 5 nm was achieved at 30 kV, comparable to transmission electron nanodiffraction.

Conclusions:

• TEFSD offers high-resolution chemical, phase, and orientation mapping capabilities.
• The technique provides simultaneous information on the chemical form, orientation, and coherency of precipitates.
• TEFSD is a powerful tool for characterizing nanoscale materials, such as precipitates in aluminium-lithium alloys.