MICROSTRUCTURE OF VERMICULAR GRAPHITE IN CAST IRON

An observation under TEM was carried out of the hetero-particles and stripes inside of the vermicular graphite in cast iron specimens which were prepared by isothermally quenching in ice-salt-water.The hetero-particles and stripes,composed of almost pure Fe and a little Si, were found in the regions of the growth direction changing of the vermicular graphite.Many twins and dislocations were also observed to contribute to changing the growth direction and to providing the growth steps of the graphite respectively.