ENGR 100 Lecture Notes - Lecture 30: Burgers Vector, Grain Boundary, Atomic Ratio
Document Summary
The magnitude and direction of lattice distortion associated with a dislocation are specified by its burgers vector, b. The relative orientations of burgers vector and dislocation line are: perpendicular for edge, parallel for screw, neither perpendicular nor parallel for mixed. (this is shown in the figures above) Within the vicinity of a grain boundary (which is several atomic distances wide), there is some atomic mismatch between two adjacent grains that have different crystallographic orientations. For a high-angle grain boundary, the angle of misalignment between grains is relatively large; this angle is relatively small for small-angle grain boundaries. Across a twin boundary, atoms on one side reside in mirror-image positions of atoms on the other side. A solid solution may form when impurity atoms are added to a solid. The original crystal structure is retained and no new phases are formed. Interstitial solid solutions form for relatively small impurity atoms.
