Mössbauer Effect in Iron-Carbon Martensite Structure

Abstract

The Mössbauer spectra in iron-carbon martensite could be resolved into four components arising from the 1st, 2nd, (3, 4)th neighboring iron atoms for the carbon atoms and the remnant iron atoms. The carbon atoms were found to cause localized changes of electronic states of the surrounding iron atoms. The internal magnetic field, isomer shift and quadrupole splitting for the first neighbors largely deviated from those for pure iron, i.e. , 265±2 KOe, -0.03±0.05 mm/sec and 0.13±0.05 mm/sec, respectively, suggesting the covalent admixture between the iron and carbon atoms. The internal fields and isomer shifts for the 2nd and (3, 4)th neighbors also deviated slightly from those of pure iron, but with the sign opposite to those for the 1st neighbors. The quadrupole splittings for them were nearly zero, which mean that the positive charge of a carbon ion is almost screened out within a distance of the order of 2Å.