STUDY OF THE SURFACE RELIEF EFFECTS ASSOCIATED WITH GRAIN BOUNDARY ALLOTRIOMORPHS BY SCANNING TUNNELING MICROSCOPY
仿晶型铁素体表面浮凸的扫描隧道显微镜研究

In this paper, surface relief effects associated with grain boundary allotriomorph (GBA) in an Fe-0.37C (mass fraction,%) steel were investigated by scanning tunneling microscopy (STM) for the first time. It was discovered that GBA does produce surface reliefs. The surface reliefs originate only from the GBA, not from both the GBA and its slip accommodation which took place in the matrix. The GBA which exhibits the surface relief is only developed into one austenite grain, and the GBA in adjacent austenite does not produce surface relief effects. This means that the GBA/austenite interface is coherent or partially coherent, but the interface between the GBA and the adjacent austenite may be incoherent. The height of surfaCe reliefs is 157-352 nm, and the maximum shape deformation is 0.37. On the broad face of the GBA exist super ledges, whose height is 300 um. The configuration of edge-to- edge sympathetic nucleation is commonly observed in GBAs. All the experimental results indicate that GBA is formed by a sympathetic nucleation-ledgewise growth mechanism.