EBSD investigation on the evolution, of microstructure and grain boundaries in coarse-grained Ni-48Al upon large deformation at elevated temperature

摘要

The evolution of microstructure and grain boundaries were investigated in coarse-grained Ni-48Al intermetallics during plastic deformation at 1075 degrees C with the initial strain rate of 1.5 x 10(-3) s(-1) using electron backscatter diffraction (EBSD) technique. Before deformation, most grain boundaries were high-angled (HAGBs), with several particular angles being predominant. During initial deformation, low-angle grain boundaries (LAGBs) with misorientation less than 5 degrees began to evolve. The misorientation of the newly-formed LAGBs increased with the increase of deformation, meanwhile, grain boundaries with misorientations between 6 and 15 degrees were gradually observed, and finally transformed into HAGBs (misorientation angle > 15 degrees). There appeared a steady state transition from the formation of new LAGBs to the transformation into high-angle grain boundaries. As a result, the grain size was refined continuously with the deformation strain. (C) 2014 Elsevier Ltd. All rights reserved.