Abstract
Experiments were carried out on graphite spheroids by means of X-ray microprobe analysis and electron photomicrography. The results obtained were as follows:
(1) The presence of Ce and Mg in graphite spheroids and in their vicinity was investigated and it was found that there was no place in which they were present in concentrations over 0.1%.
(2) Spheroidals graphite nuclei which can be observed in the as-cast state of white iron castings were spherical when observed with an electron microscope and indicated an interesting structure when compared with after-annealed graphite spheroids.
(3) The white cores in graphite spheroids is due to decomposition of cementite which has been drawn in during graphitization, but it has been shown as a result of investigation of the distribution of C, Si and Fe that the white core of the sphere is rich in Fe, and a small amount of Si was detected. Also, the white core can be observed by back scattering electron and its presence can also be confirmed by electron photomicrography.
(4) The size of the graphite spheroid is approximately the same as that of nodular iron and is about 20∼60 μ.
