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Curie temperature in Fe(Ni)Nb based mechanically alloyed materials

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A conventional thermogravimeter has been adapted with a small magnet to detect the Curie temperature, T C. The measurements were performed in several Fe(Ni)NbB alloys developed in a nanocrystalline form by mechanical alloying. The B addition favors a slight diminution (10-20°C), and the Ni addition the existence of three transitions related with bccFe, fcc(Fe-Ni) abd fccNi-rich environments. Furthermore, complementary analysis were performed by means of differential thermal analysis, scanning electron microscopy with energy dispersive X-ray microanalysis and by induced coupled plasma. Small contamination was found. A mass increase (about 1 mass%) was detected by thermogravimetry related to oxidation. Analysis allows us to state the inhomogeneity of the alloys obtained after 80 h of milling

Financial support from MICYT (project No. MAT2003-08271) and DURSI (project 2001SGR-00190) is acknowledged

Springer Verlag