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Title: Improving single-crystal orientation determination for advanced nickel-based alloys.

Author: Clay, K*, Jackson, J D*, Quested, P N, Morrell, R
(An asterisk (*) after an author's name indicates a non-NPL author)

Source: Measurement Good Practice Guide No. 112 ,April 2009.
ISSN: 1368-6550

Abstract: This Good Practice Guide describes the determination of single-crystal orientation measurements for single-crystal nickel-base castings by back and side-reflection X-ray diffraction (Laue). These measurements check the quality of the castings against specifications set by the OEMs for the foundries. For quality control three parameters are determined: 1. The angle between a reference direction in the component, defining the preferred direction of solidification, and the closest <100> direction. (q). 2. Less commonly, the angle between a second reference direction in the plane perpendicular to the original reference direction (a) and/or a <001> direction (k). 3. For single crystals with more than one grain a measurement of the misorientation or disorientation between adjacent grains (R). The guide contains information about the definition of orientation parameters; principles of back-reflection and side-reflection Laue systems; calibration standards; system alignment; calibration; validation and uncertainty of measurements with a final section on making the measurements. The definition of primary angles is based upon European practice but a comparison with two definition conventions used in the USA is included.

Document Type: Guide


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