Homogenisation behaviour ofNd2(Fe0.98Nb0.02)14B alloy
Ahmed, F.M.; Edgley, D.S.; Gutfleisch, O.; Harris, I.R.
Magnetics, IEEE Transactions on
Volume 30, Issue 2, Mar 1994 Page(s):616 - 618
Digital Object Identifier 10.1109/20.312353
Summary:The effects of the homogenisation conditions on the microstructure
of a Nd2(Fe0.98Nb0.02)14B
alloy have been investigated. In the as cast condition the
microstructure of the alloy contains four phases, the Nd2Fe
14B matrix phase, a Nb-containing ternary phase (Nb26
Fe32B42), Nd-rich regions and free iron. In
contrast, the homogenised alloy contains only the first two phases and
very small amounts of the Nd-rich phase. The Nb26Fe32
B42 ternary phase was found to originate (nucleate) in
the heart of the free iron phase which provides strong evidence for the
role of Nb in the removal of free iron from the microstructure. The
electrical resistivity of the alloy was measured at regular intervals
during the homogenisation process at 1000°C and these studies
revealed that, after 40 hours, the alloy was completely homogenised and
this was in a good agreement with the microstructural studies. The
resistance measurements also indicated a degree of anisotropy in the
as-cast material and there was a maximum in resistance at an
intermediate stage which could indicate an age hardening process. The
resistance was found to correspond to a microhardness value
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