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Digital Image Correlation of 2D X-ray Powder Diffraction Data for Lattice Strain Evaluation

DOI: 10.3390/ma11030427 DOI Help

Authors: Hongjia Zhang (University of Oxford) , Tan Sui (University of Oxford; University of Surrey) , Enrico Salvati (University of Oxford) , Dominik Daisenberger (Diamond Light Source) , Alexander J. G. Lunt (University of Oxford) , Kai Fong (Singapore Institute of Manufacturing Technology (SIMTech)) , Xu Song (Singapore Institute of Manufacturing Technology (SIMTech)) , Alexander Korsunsky (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Materials , VOL 11

State: Published (Approved)
Published: March 2018

Open Access Open Access

Abstract: High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position information is required for lattice strain evaluation. The multi-step conversion process is likely to lead to increased errors associated with the ‘caking’ (radial binning) or fitting procedures. A new method is proposed here that relies on direct Digital Image Correlation analysis of 2D X-ray powder diffraction patterns (XRD-DIC, for short). As an example of using XRD-DIC, residual strain values along the central line in a Mg AZ31B alloy bar after 3-point bending are calculated by using both XRD-DIC and the conventional ‘caking’ with fitting procedures. Comparison of the results for strain values in different azimuthal angles demonstrates excellent agreement between the two methods. The principal strains and directions are calculated using multiple direction strain data, leading to full in-plane strain evaluation. It is therefore concluded that XRD-DIC provides a reliable and robust method for strain evaluation from 2D powder diffraction data. The XRD-DIC approach simplifies the analysis process by skipping 2D to 1D conversion, and opens new possibilities for robust 2D powder diffraction data analysis for full in-plane strain evaluation.

Journal Keywords: 2D X-ray powder diffraction; strain measurement; Digital Image Correlation; 3-point bending

Subject Areas: Technique Development, Physics

Instruments: I15-Extreme Conditions


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