STRUCTURE AND PHASE FRACTION OF MELT-SPUN HIGH-CARBON FE-NI-C ALLOYS

The structure and the phase fractions of as-quenched Fe-Ni-C ribbons w ere studied using Mossbauer spectroscopy, X-ray analysis and SEM. The phase fractions obtained from Mossbauer spectra show presence of the g amma-austenite, Theta, chi and epsilon carbides, a pre-precipitation c arbide stage and alpha-martensite. The amount of each phase depends on the chemical composition. An amorphous phase was not found. The possi ble existence of an hcp iron phase is discussed in connection with the appearence of the pre-precipitation stage of carbides. A comparison o f the phase fractions with the phase diagram enabled a model of phase growth during cooling to be proposed. The measurements of microhardnes s can be explained well by the amount of the phases.