ELECTRON BACKSCATTER DIFFRACTION (EBSD)

Presenter: Imtiaz AliRegistration No. : 400360

Contents

Introduction to EBSD Brief History Principal system components How the Pattern is Formed? EBSP - Electron Backscatter

Diffraction Patterns Operating conditions Uses of EBSD Summary

Introduction to EBSD

EBSD is a technique that allows: Crystallographic Orientations Misorientations Texture trends Grain size and boundary types Phases

Brief History 1928 Kikuchi lines observed in TEM 1954 Alam: patterns obtained in TEM 1973 Venebles: patterns recorded on film in SEM 1980 Patterns imaged with low light TV cameras 1990 Automatic pattern solving using Hough transform Present day

Local orientation and misorientations measurements Crystal Orientation Mapping (COM) Special grain boundaries imaged Special textures revealed Grain sizing

Principal system components

Sample tilted at 70° from the horizontal. A phosphor screen. A sensitive CCD video camera A vacuum interface for mounting the

phosphor and camera in an SEM port. Electronic hardware that controls the SEM,

including the beam position, stage, focus, and magnification.

A computer to control EBSD experiments, analyze the EBSD pattern and process and display the results.

Principal system components

How the Pattern is Formed

High energy electrons are elastically scattered by atomic planes in a crystallographic sample.

Operating conditions

Accelerating Voltage : 15-30 kV Beam current : 1-15 nA Collection angle : 70° Working distance : 10-25 mm

EBSP - Electron Backscatter Diffraction Patterns

Si single crystal As the sample is rotated, the pattern

changes to reflect the new orientaion

Uses of EBSD

Quantitative micro structural data Phase identification Strain analysis Maps

Summary EBSD has become a well established micro

structural analytical technique. EBSD mapping can be used to explore the

processing microstructure – properties relationships.

EBSD can be used on most crystalline materials

Grain size, sample tilt, and sample preparation are the primary limitations of the technique.

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