Determination of macroscopic stress from diffraction experiments: A critical discussion

• Published in: Journal of applied physics Vol. 128; no. 2
• Main Authors: Mishurova, Tatiana, Bruno, Giovanni, Evsevleev, Sergei, Sevostianov, Igor
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 14.07.2020
• Subjects: Applied physics; Diffraction; Elastic properties; Isotropy; Materials science; Mathematical analysis; Measurement methods; Synchrotron radiation; Tensors; Titanium base alloys
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0009101

The paper is motivated by some inconsistencies and contradictions present in the literature on the calculation of the so-called diffraction elastic constants. In an attempt at unifying the views that the two communities of Materials Science and Mechanics of Materials have on the subject, we revisit and define the terminology used in the field. We also clarify the limitations of the commonly used approaches and show that a unified methodology is also applicable to textured materials with a nearly arbitrary grain shape. We finally compare the predictions based on this methodology with experimental data obtained by in situ synchrotron radiation diffraction on additively manufactured Ti-6Al-4V alloy. We show that (a) the transverse isotropy of the material yields good agreement between the best-fit isotropy approximation (equivalent to the classic Kröner's model) and the experimental data and (b) the use of a general framework allows the calculation of all components of the tensor of diffraction elastic constants, which are not easily measurable by diffraction methods. This allows us to extend the current state-of-the-art with a predictive tool.