20-21 November 2014
National Centre for Synchrotron Science
Australia/Melbourne timezone
Save the date: User Meeting 2015 - 26-27 November

Quantitative analysis of spotty diffraction rings and application to corrosion studies of steel

21 Nov 2014, 11:15
NCSS Seminar Room ()

NCSS Seminar Room

Oral Energy Materials Energy Materials


Dr Bridget Ingham (Callaghan Innovation)


Spotty diffraction rings are symptomatic of large-grained polycrystalline materials. Analysis of these rings falls into a void between single crystal and powder diffraction methods, and is usually dismissed or discussed only briefly and in a qualitative fashion. Recently, we have developed statistical methods for quantitatively analysing the ‘spottiness’ of diffraction rings, such as those observed during CO2 corrosion of steel in aqueous solutions under electrochemical control. These include the normalised roughness and the fractal dimension of the diffraction ring, obtained from 2D diffraction images. Statistical measures obtained for diffraction patterns calculated from theoretical crystallite size distributions are compared to those obtained for experimental data. This illustrates that the corrosion mechanism relies on the formation of surface roughness, which proceeds via preferential dissolution of small grains. References: B. Ingham, ‘Statistical measures of spottiness in diffraction rings’, J. Appl. Cryst. 2013, 47, 166-172. M. Ko, B. Ingham, N. Laycock and D. E. Williams, ‘In situ synchrotron X-ray diffraction study of the effect of microstructure and boundary layer conditions on CO2 corrosion of pipeline steels’, Corrosion Sci. (submitted).
Keywords or phrases (comma separated) XRD, diffraction, analysis, corrosion

Primary author

Dr Bridget Ingham (Callaghan Innovation)

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