Matsuda Kenji

TEM Observation of Spheroidal Graphite in Ductile Cast Iron

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.

Influence of Trace Sb Addition in Ductile Cast Iron

Since the ductile cast iron has the characteristics, such as outstanding mechanical properties, it is broadly used for auto parts, machine structure parts and so on. RE elements are added as spheroidizing treatment. However, it is reported that it promotes growth of the chunkey graphite. Antimony is added as a purpose to prevent formation of the chunkey graphite. In this study, the influence of antimony to mechanical property and graphite formation on ductile cast iron is researched by changing quantity of antimony addition. In a scanning electron microscope (SEM) observation, the surface form of the spheroidal graphite was obtained the coarse surface in basic alloy, while the smooth surface was obtained in 0.097Sb. In transmission electron microscope (TEM) observation, internal structure was observed the shape of a block with the spheroidal graphite of the basic alloy, while the internal structure was observed smoother with the spheroidal graphite in 0.097Sb.