Microstructural analysis of severely deformed materials using X-Ray diffraction and EBSD

N. S. DE VINCENTIS; M. C. AVALOS; E. BENATTI; A. KLIAUGA; M. FERRANTE; H-G. BROKMEIER; R.E. BOLMARO

Campinas

Otro; Sao Paulo School of Advanced Science on Recent Developments in Synchrotron Radiation; 2015

Severe plastic deformation techniques improve the mechanical properties of a material by affecting its microstructure, decreasing domain sizes and accumulating defects, mostly dislocation arrays and stacking faults. The complexity of such microstructure requires the combination of different techniques for a complete analysis, including both local and global microstructural information. For the former analysis, Electron Back Scatter Diffraction (EBSD) allows not only to observe the microstructure at nanometric resolution but also to characterize local crystalline orientation and misorientation. This information can be correlated to the microstructural analysis carried out by global techniques, such as X-ray diffraction; through peak broadening and shape analysis, this technique allows to quantify the presence of different microstructural features affected by deformation, such as domain sizes, dislocation and stacking fault densities, and compactness of dislocation arrays [1][2]. This analysis can be performed on diffraction data obtained in various instruments with different wavelengths and angular dispersions, determining in this way the sensitivity of the technique to the energy and brilliance of the instruments. In particular, this analysis can be carried out in data obtained from different diffracting planes in the samples, allowing the study of the anisotropic microstructure determined by deformation through the construction of Generalized Pole Figures (GPFs) [3]. The analysis was performed on F138 stainless steel samples deformed by equal-channel angular pressing at room temperature and 300°C, in order to compare grain refinement and twin and dislocation boundary development. The microstructural anisotropy determined by cold rolling was also analyzed for Al, Cu and F138 steel samples, by the determination of GPFs. The diffraction patterns were obtained at an X?Pert PRO diffractometer and at LNLS and DESY synchrotron facilities.