鋳鉄の凝固時の黒鉛生成に及ぼすテルルの影響

抄録

  The morphological change of graphite in gray cast iron during solidification when the melt was alloyed with pure tellurium was studied by using scanning electron microscope. It seemed that the adsorption of tellurium on the prism plane of graphite crystal suppressed the crystal growth on the plane so that it accelerated the growth of graphite crystal on c-plane in c-axis direction. Subsequently, a hexagonal stacked structure of graphite crystal is observed on a deep etched alloy having higher content of tellurium when slow cooling but is not so remarkable in fast cooling. The same results on morphological change of graphite during solidification are obtained both in nickel-carbon hypereutectic alloy and iron-carbon-silicon hypereutectic alloy. Moreover, it can be assumed that in eutectic reaction of hypoeutectic iron, there is some suppression of crystal growth of graphite in the c-axis direction by the cooperative growth of γ-dendrite by tellurium addition which causes the supercooling of the melt and leads to the eutectic reaction in the meta-stable system.