Interface-sensitive conversion-electron Mossbauer study of ion-beam mixing at the Fe-Al interface

Godbole, V. P. ; Chaudhari, S. M. ; Ghaisas, S. V. ; Kanetkar, S. M. ; Ogale, S. B. ; Bhide, V. G. (1985) Interface-sensitive conversion-electron Mossbauer study of ion-beam mixing at the Fe-Al interface Physical Review B, 31 (9). pp. 5703-5711. ISSN 0163-1829

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Official URL: http://prb.aps.org/abstract/PRB/v31/i9/p5703_1

Related URL: http://dx.doi.org/10.1103/PhysRevB.31.5703

Abstract

Ion-beam-induced atomic mixing and the effect of thermally activated transformations at the Fe-Al interface have been studied for the first time with use of the technique of conversion-electron 57Fe Mossbauer spectroscopy (CEMS). A concept of interface-sensitive CEMS which exploits the deposition of a thin (~50-A°) layer of iron enriched to 95.45.% of 57Fe at the interface between the aluminium substrate and an overlayer of natural iron (containing only 2.2% of 57Fe) has been introduced and used in the present investigations. CEMS spectra of the as-deposited sample, fitted in terms of the distribution of hyperfine fields at 57Fe nuclei show that not all the 57Fe atoms in the interface region see the environment as in α-Fe but have one or more aluminium neighbors. The interface layers are transformed on bombardment with 100-keV Ar+ ions at a dose of ~1016 ions/cm2 into a random metastable alloy having an average composition of Fe55Al45. 57Fe atoms in this alloy experience a variety of environments ranging from dimers in Al matrix at one end to that typically characteristic of α -Fe at the other. This alloy does not show any phase precipitation on vacuum annealing at 300 and 400 °C for 20 min. However, on annealing at 500°C, a sudden precipitation of α-Fe and Fe3Al phases is seen. On further annealing of the sample at 600 °C, Fe3Al phase is seen to decompose to give iron clusters. These results of CEMS measurements have been confirmed by small-angle x-ray-diffraction studies. A non-interface-sensitive CEMS study has also been performed to investigate the dose dependence of ion-beam mixing.

Item Type:Article
Source:Copyright of this article belongs to American Physical Society.
ID Code:26915
Deposited On:08 Dec 2010 13:00
Last Modified:19 May 2011 09:17

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