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Crystallization behavior of some melt spun Nd–Fe–B alloys

Published online by Cambridge University Press:  31 January 2011

M. T. Clavaguera-Mora ,
M. D. Baró ,
S. Suriñach  and
N. Clavaguera
M. T. Clavaguera-Mora
Affiliation:
Física de Materials, Dept. Física, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain
M. D. Baró
Affiliation:
Física de Materials, Dept. Física, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain
S. Suriñach
Affiliation:
Física de Materials, Dept. Física, Universitat Autònoma de Barcelona, 08193-Bellaterra, Spain
N. Clavaguera
Affiliation:
Dept. Estructura i Constituents de la Matèria, Facultat de Física, Diagonal 647, 08028-Barcelona, Spain
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Abstract

The kinetics of crystallization of four amorphous (or partially amorphous) melt spun Nd–Fe–B alloys induced by thermal treatment is studied by means of differential scanning calorimetry and scanning electron microscopy, In the range of temperatures explored experimentally, the crystallization process is thermally activated and generally proceeds in various stages. The Curie temperature and the crystallization behavior have been measured. The apparent activation energy of crystallization of most of the crystallization stages has been determined for each melt spun alloy. The explicit form of the kinetic equation that best describes the first stage of crystallization has been found. It follows in general the Johnson-Mehl-Avrami-Erofe'ev model, but clear deviations to that model occur for one alloy. Scanning electron microscopy demonstrates that preferentially hetereogeneous nucleation occurs at the ribbon surface which was in contact with the wheel. From crystallization kinetics results the lower part of the experimental time-temperature-transformation curves for all studied alloys are deduced and extrapolated to the high temperature limit of their range of validity, also deduced.

Type
Articles
Information
Journal of Materials Research , Volume 5 , Issue 6 , June 1990 , pp. 1201 - 1206
Copyright
Copyright © Materials Research Society 1990

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References

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