Fe-C-Si合金の恒温凝固線図について

抄録

In a previous paper it is shown that a solidification process which has been termed the “K-type non-eutectic reaction” proceeds prior to the eutectic reaction in Fe-C-Si alloys undercooled severely.
In this investigation, the freezing behavior in the same alloys undercooled at various temperatures below the theoretical freezing point has been studied by using an isothermal solidification technique, and solidification processes termed the “G-type non-eutectic reaction” and the “C-type non-eutectic reaction” have been demonstrated.
The similarity between the G-type non-eutectic reaction and the C-type non-eutectic reaction does exist in the solidification pattern of “crystallization of austenite in the melt and precipitation of graphite in the supersaturated austemte”. In the G-type non-eutectic solidification process, however, excess carbon in the supersaturated austenite is precipitated on the eutectic graphite phase formed by the graphite-eutectic reaction, whereas in the C-type non-eutectic reaction it is precipitated along the austenite-cementite interface formed by the cementite-eutectic reaction.
From the experimental data obtained in this investigation, an isothermal solidification diagram for the alloy tested has been constructed. The solidification diagram consists of three sets of freezing curves; the first is for the austenite-graphite eutectic reaction, the second is for the austenite-cementite eutectic reaction and the third is for the K-type non-eutectic reaction.