Meaning
Analysis of crystalline materials in a scanning electron microscope provides high-resolution data on local crystallographic orientations. Utilizing electron backscatter diffraction allows researchers and quality control engineers to map grain boundaries, identify phases and measure local texture. The technique relies on the elastic scattering of electrons from the lattice planes, which forms characteristic Kikuchi patterns on a phosphor screen.
These patterns are indexed to determine the orientation of the crystallite under the beam.
Orientation Mapping
Spatial resolution of this method extends to tens of nanometers, permitting the detailed examination of fine-grained or severely deformed alloys. By scanning the beam across a defined area, electron backscatter diffraction generates rich datasets that reveal misorientation angles between adjacent grains. This capability is used to quantify the fraction of recrystallized grains and the density of coincidence site lattice boundaries.
Microstructural Audit
Manufacturing facilities deploy this analytical technique to assess the quality of thermomechanical processing runs and heat treatment cycles. Standard evaluations verify the absence of unwanted deformation textures that could compromise the ductility of the final components. Relying solely on bulk diffraction methods can miss localized microstructural inhomogeneities that lead to service failures.
Process Control
Implementing this detailed analysis during the early stages of alloy development helps optimize the rolling and annealing parameters. High-throughput scanning reduces the time needed to qualify new supplier batches and ensure consistency across different production lots. Although the capital cost of the equipment is substantial, preventing the deployment of substandard metal structures into critical aerospace components offsets the initial investment.
Verifying grain structures before starting expensive machining runs protects the manufacturer from incurring unnecessary finishing costs on defective blanks.
