Lect17_notes

17 grain boundaries the crystal grain has the same

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Unformatted text preview: 164 – XRD, SEM & Microanalysis: Lecture 17 ! 16 EBSD Patterns From Polycrystalline Samples! ! ! ! ! ! ! CBEMS 164 – XRD, SEM & Microanalysis: Lecture 17 ! 17 Grain Boundaries! •  The crystal (grain) has the same structure of each side of the boundary but the crystals on each side of the boundary have different orientations •  The misorientation between the two grains is characterized by an axis of rotation (that is common between the two grains) and an angle of rotation –  Axis/angle pair CBEMS 164 – XRD, SEM & Microanalysis: Lecture 17 ! 18 Grain Boundary! •  A plane between two grains in a polycrystalline material •  The crystal on each side of the boundary has a different orientation •  To transform one orientation to the other, need to identify an axis and an angle of rotation - 2 degrees of freedom •  Boundary plane has 3 degrees of freedom •  5 parameters needed to define a boundary CBEMS 164 – XRD, SEM & Microanalysis: Lecture 17 ! 19 CBEMS 164 – XRD, SEM & Microanalysis: Lecture 17 ! 20 Grain Size Determination! ! ! ! ! ! ! An Orientation Image/Map! ! ! ! ! ! ! •  Beam scans sample pixel by pixel –  As with SEM imaging •  EBSD pattern acquired at each pixel •  Pattern indexed and orientation of grain with respect to specimen surface calculated (automated) CBEMS 164 – XRD, SEM & Microanalysis: Lecture 17 ! 21 CBEMS 164 – XRD, SEM & Microanalysis: Lecture 17 ! 22 Grain Boundary Character! ! ! ! ! ! ! •  Color assigns type –  Yellow - low angle - 0-5° –  Purple 5-15° –  Red - 3 –  Green - >3...
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This note was uploaded on 01/16/2014 for the course CBEMS 164 taught by Professor Porter,j during the Fall '08 term at UC Irvine.

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