Phase stability of (Fe80Nb6B14)(0.9)Tb-0.1 bulk nanocrystalline magnet

Abstract

The paper refers to phase stability of the (Fe80Nb6B14)0:9Tb0:1 bulk nanocrystalline alloys prepared using the vacuum suction casting technique. The samples were in the form of rods with diameters d = 2, 1.5, 1 and 0.5 mm. Heating up to 900 K reveals structural changes that occur at temperatures above 680 K (DSC and M(T) measurements). The phase analysis, using Mössbauer spectra, indicates the decrease of Tb2Fe14B and increase of Fe content in the samples after the heat treatment. The most stable is the alloy with d = 1 mm, where the formation of -Fe phase was not observed. The decrease of d causes signi cant hardening i.e. coercive eld increases from 0.57 T to 2.66 T for d = 2 mm and d = 0:5 mm, respectively.