A Subsecond Pulse Heating Technique for the Study of Solid-Solid Phase Transformations at High Temperatures: Applications to Iron.

摘要

A system based on an accurate pulse heating technique is described that can be used for investigation of solid-solid phase transformations at temperatures above 1500K. The system is capable of heating the specimen from room temperature to its melting point in less than 1 s and of measuring the pertinent experimental quantities every 0.4ms with a full-scale signal resolution of approximately one part in 8000. Specimen temperature is measured with a high-speed photoelectric pyrometer and recordings of experimental quantities are made with a high-speed digital data acquisition system. Application of the technique to investigations at the gamma to delta transformation point of iron is described. Measurements yielded the following results: 1683K for the transformation temperature, 890 j/mol for the transformation energy, and 0.36 for the normal spectral emittance (at 0.65 micrometers at the transformation point). (Author)