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Irreversible transformation in as-cast FeAl B2-ordered alloy obtained by melt spinning

Published online by Cambridge University Press:  31 January 2011

E. Bonetti
Affiliation:
INFM-Dipartimento di Fisica, Universita’ di Bologna, viale Berti Pichat 6/2, I-40127 Bologna, Italy
R. Montanari
Affiliation:
INFM-Dipartimento di Ingegneria Meccanica, Universita’ di Roma “Tor Vergata,”via di Tor Vergata 110, I-00133 Roma, Italy
C. Testani
Affiliation:
Centro Sviluppo Materiali, via di Castel Romano 100–102. I-00129-Roma, Italy
G. Valdrè
Affiliation:
INFM-Dipartimento di Fisica, Universita’ di Bologna, viale Berti Pichat 6/2, I-40127 Bologna, Italyand INFM-Dipartimento di Scienze della Terra e Geo-Ambientali, P.P. San Donato 1, Universita‘di Bologna, I-40126 Italy
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Abstract

The aim of the work described in the present paper was to investigate the microstructural stability during annealing treatments of a Fe–Al alloy obtained by melt spinning. To this purpose internal friction (IF) and dynamic modulus (Md) measurements were employed, and the results correlated with x-ray diffraction, optical microscopy, and scanning and transmission electron microscopy observations. In particular, the B2-ordered Fe–38A1–2Cr–0.015C–0.003B (in at.%) alloy was studied during repeated heating runs from room temperature to 823 K by IF and Md. The modulus exhibited a broad maximum (in the range of 600–800 K) only in the first run. On the basis of transmission electron microscopy and x-ray diffraction analysis, the irreversible transformation was explained by considering a two-stage process that occurs when vacancies in supersaturation move toward dislocations. The first stage is connected to dislocation locking; the second one is due to annihilation of some vacancies by dislocation climb.

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Articles
Copyright
Copyright © Materials Research Society 2000

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