Reobservations of ferrite recrystallization in a cold-rolled ordered Fe–50Co–10V alloy using the EBSD method

Highlights: • Recrystallization characteristics determined from multiple-analyses of EBSD data. • Austenite transformation starts at a lower temperature than recrystallization. • Ferrite recrystallization proceeds by intense recovery and continuous mechanism. • Ferrite recrystallization follows sigmoidal kinetics but is slow even at 750 °C. -- Abstract: Even after extensive research for decades on cold-rolled magnetic Fe–Co–V alloys, many aspects of ferrite recrystallization are still unclear. In order to analyse the progress of recrystallization in an Fe–50Co–10 V (in wt.%) alloy, different thermal cycles were conducted for an 86% cold-rolled thin sheet (∼140 μm). A comprehensive phase characterization and texture analysis were carried out using X-ray diffraction and scanning electron microscopy. To investigate the ferrite recrystallization during concurrent ordering and austenite transformation processes, the utilization of several methods such as the Kernel Average Misorientation and Grain Orientation Spread analyses together with grain boundary misorientation and grain size distributions, and characterization of microstructure by electron backscatter diffraction were crucial. The austenite transformation, detected to start at 500–550 °C, complicated the determination of the recrystallization kinetics; however, it was clarified by the present multi-parameter analyses. The ferrite recrystallization was found to initiate at 600 °C within 1 h and progress by the continuous recrystallization mechanism. The typical gamma-fiber texture of the cold-rolled alloy remained almost unchanged upon annealing temperatures up to 750 °C, also confirming the continuous recrystallization mechanism, similarly as the grain boundary misorientation evolution did. The recrystallization kinetics was found to follow the Avrami model with constant exponent in both ordered and disordered states. The recrystallization rate was slow, so that even after 4 h annealing in the disordered state at 750 °C, fragments of ferrite grains with straight sub-boundaries were retained.