A Study of the Mössbauer Effect during the Tempering of Iron-Carbon Martensite

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Abstract
The Mössbauer effect of 57 Fe in the iron-carbon martensite steels was measured during their tempering process, and the appearance of the ε -, χ- and cementite phases and the bonding nature in them were studied. It was clarified that the χ-carbide is formed at the tempering stage III a, the formation of which had not been fully proved in previous X-ray or magnetic measurements. It was also concluded that the electronic states of the iron atoms co-ordinating the carbon atoms in the martensite and the ε -carbide formed in the stage I are substantially the same, suggesting that the motive force in the stage I is mainly the relaxation of the large strain energy in tne martensite structure. The observed localized and additive nature of the iron-carbon interaction, which was concluded from the linear relation between the amount of the internal field reduction and the number of carbon co-ordination for iron atoms in the various phases, seems to indicate that the Alexander-Anderson-Moriya's idea is applicable to the transition metal-metalloid alloys.