ON THE TRANSFORMATION IN HIGH PURITY IRON BY SUPER-RAPID HEATING.

The A//c//3 ( alpha yields gamma ) transformation behavior during super-rapid heating of up to 10**6 degree C/sec and the isothermal transformation during heating at various temperatures over A//e//3 were investigated for a high-purity iron using newly designed apparatuses. The A//c//3 transformation temperature at a rate of 10**6 degree C/sec in a vacuum of 10** minus **6 Torr and in air was determined by a PbS cell heat radiator. It was detected that the A//c//3 point at each heating rate in vacuum is higher than in air. The A//c//3 transformation temperature rises above the equilibrium temperature with increasing heating rate up to 10**6 degree C/sec. The alpha yields gamma isothermal transformation process was continuously observed by measuring the change in electric resistance. It was considered that alpha yields gamma transformation in high-purity iron might proceed intermittently by a diffusionless mechanism.