Critical assessment 20: On carbon excess in bainitic ferrite

For several decades, the question of carbon supersaturation in bainitic ferrite has attracted the attention of physical metallurgists. Originally, this was associated with excess carbon due to the displacive nature of phase transformation and its subsequent trapping at defects in bainitic ferrite. The development of advanced experimental techniques, such as atom probe tomography and in situ synchrotron and neutron X-ray diffraction, has provided new insights into carbon distribution within bainitic ferrite. Possible explanations for carbon excess in solid solution are discussed, and the pathways for the future advancement of this research question are suggested.