An In-situ method for the study of strain broadening usingsynchrotronx-ray diffraction
A tensonometer for stretching metal foils has beenconstructed for the study of strain broadening in x-ray diffraction lineprofiles. This device, which is designed for use on the powderdiffractometer in Station 2.3 at Daresbury Laboratory, allows in-situmeasurements to be performed on samples under stress. It can be used fordata collection in either transmission or reflection modes using eithersymmetric or asymmetric diffraction geometries. As a test case,measurements were carried out on a 18mum thick copper foil experiencingstrain levels of up to 5 percent using both symmetric reflection andsymmetric transmission diffraction. All the diffraction profilesdisplayed peak broadening and asymmetry which increased with strain. Themeasured profiles were analysed by the fundamental parameters approachusing the TOPAS peak fitting software. All the observed broadenedprofiles were modelled by convoluting a refineable diffraction profile,representing the dislocation and crystallite size broadening, with afixed instrumental profile pre-determined usinghigh quality LaB6reference powder. The de-convolution process yielded "pure" sampleintegral breadths and asymmetry results which displayed a strongdependence on applied strain and increased almost linearly with appliedstrain. Assuming crystallite size broadening in combination withdislocation broadening arising from fcc a/2<110>111 dislocations,we have extracted the variation of mechanic al property with strain. Theobservation of both peak asymmetry and broadening has been interpreted asa manifestation of a cellular structure with cell walls and cellinteriors possessing high and low dislocation densities.
- Research Organization:
- COLLABORATION - Diamond LightSource/UK
- Sponsoring Organization:
- USDOE Director. Office of Science. Basic EnergySciences
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 928773
- Report Number(s):
- LBNL--62127; BnR: KC0204016
- Journal Information:
- Journal of Applied Crystallography, Journal Name: Journal of Applied Crystallography Journal Issue: 4 Vol. 40; ISSN JACGAR; ISSN 0021-8898
- Country of Publication:
- United States
- Language:
- English
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