Microstructural evidence of abnormal grain growth by solid-state wetting in Fe-3%Si steel

Abstract

In this investigation, the mechanism of abnormal grain growth in Fe-3%Si steel was based on the microstructure evolution at the growth front of grains undergoing the abnormal growth. The most striking feature in the growth of abnormal grains was the penetration along the grain boundary of neighboring grains. This is energetically possible if the energy of the penetrated grain boundary is higher than the sum of the energy of two other grain boundaries shared by the penetrating abnormal grain. Along the growth front of an investigated abnormally growing grain, 15 out of 1381 triple junctions showed the clear microstructural evidence of the grain boundary penetration by the abnormal grain. Misorientation measurements of 34 penetrated grain boundaries using electron backscattered diffraction showed that not a single boundary has a low angle, implying that the penetrated grain boundaries have the high energy. These results are best explained by the abnormal grain growth with solid-state wetting.