TEM observation of spheroidal graphite in ductile cast iron

Abstract

This research produced typical ductile cast iron, and observed spheroidal graphite in this ductile cast iron by electron microscopes. For scanning electron micrographs of graphite morphology, the metallic matrix was dissolved away by deep etching in a 10% nitric acid solution. The result observed by scanning electron microscope (SEM), spheroidal graphite was patterned indented surface. High magnification image of the spheroidal graphite was observed graphite flakes sticking to surfaces. The cross-sectional transmission electron microscope (TEM) specimens of spheroidal graphite were prepared by Focused Ion Beam (FIB) system method. TEM dark field image using strong graphite (0002) diffraction was obtained from cross-section of the central part in spheroidal graphite, and it was found that a growth structure of a cone in spheroidal graphite radiated to outwards from the central part along the direction of c-axis of the graphite structure. In addition, with a cone radiated to outwards from the central part, graphite structure slightly rotated along c-axis of itself. Cross section of the outside part in spheroidal graphite was observed polycrystals whose c-axis of the graphite structure was the same direction.