Bragg edge determination for accurate lattice parameter and elastic strainmeasurement

Citation
A. Steuwer et al., Bragg edge determination for accurate lattice parameter and elastic strainmeasurement, PHYS ST S-A, 185(2), 2001, pp. 221-230
Citations number
13
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHYSICA STATUS SOLIDI A-APPLIED RESEARCH
ISSN journal
00318965 → ACNP
Volume
185
Issue
2
Year of publication
2001
Pages
221 - 230
Database
ISI
SICI code
0031-8965(20010616)185:2<221:BEDFAL>2.0.ZU;2-D
Abstract
The transmission spectrum of thermal neutrons through a polycrystalline sam ple displays sudden, well-defined increases in intensity as a function of n eutron wavelength. These steps, known as Bragg edges, occur at the point at which the neutron wavelength exceeds the Bragg condition for coherent scat tering from the respective lattice planes, and can be easily observed using the time-of-flight method. Accurate location of these edges and determinat ion of their magnitude and shape can be used to extract information about t he stress state, texture and phases present in the material. This paper des cribes a method for analysing these edges singly and collectively, using a Pawley-type refinement. Furthermore, experimental trials are presented whic h demonstrate the utility of the method for the accurate measurement of lat tice spacings, and thus strain. These trials include measuring the lattice parameter in Cu/Zn alloys as a function of Zn content, and the determinatio n of elastic strain of an iron rod under tensile/compressive straining. In the former case the results are compared with Bragg diffraction peak measur ements made on HRPD and in the latter case with conventional strain gauge m easurements.