MOSSBAUER EFFECT IN IRON-CARBON AND IRON-NITROGEN ALLOYS.
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF METALLURGY
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Interstitial solid solutions of carbon and nitrogen in iron were analyzed by Mossbauer spectroscopy. In both allotropic forms, austenite gamma and martensite alpha, electric quadrupole effects were observed, arising from a repopulation of electrons among the d-orbitals of iron atoms adjacent to the interstitial atoms. In carbon austenite, the quadrupole effect of e sq qQ2 0.625 mmsec for iron atoms which are first neighbors of carbon atoms. In nitrogen-austenite, the quadrupole effects are smaller but an appreciable positive isomer shift is observed for iron atoms which are first neighbors of nitrogen atoms. This suggests that these iron atoms have more d-electrons due to some covalent bonding with nitrogen as exists in the isomorphous Fe4N phase. Carbon shows a positive and nitrogen a negative ion behavior in both martensite and in austenite. The c-axis is a direction of difficult magnetization in both Fe-C and Fe-N martensites.
- Metallurgy and Metallography
- Atomic and Molecular Physics and Spectroscopy