Structure of Boron-nitride Precipitated in the 0.53%C Steel and Graphite Nucleated on Its Surface

It was reported previously that BN acted as nucleation site for graphitization of cementite. Lattice images of BN and graphite were observed by FE-TEM and electron diffraction analysis was conducted on 0.53C-1.2Si-0.3Mn- 0.0017B steel. It was shown that [0001] axes exist radially in a BN polycrystal and (0001) planes are parallel to surface of a BN crystal. After graphitization treatment of 1.8ks at 973K, nucleation of graphite as to making (0001) planes of graphite parallel to (0001) planes of BN and growth as to making basal planes of hexagonal crystals of graphite parallel to surface. It was shown that BN offers its surface as effective nucleation site for graphitization.