Synthesis of melt-spun rare-earth transition-metal intermetallics with Nd-3(Fe,Ti)(29)-type structure

Rare-earth transition-metal intermetallics with the Nd-3(Fe,Ti)(29)-type st ructure with R=Nd, Pr have been synthesized. The as-spun ribbons show a bro ad magnetic transition between 400 and 500 K. After annealing over a range of temperatures, 723-1373 K, and for times in the range 15-50 min, multipha se samples with the R-3(Fe,Ti)(29), R(Fe,Ti)(12), R-2(Fe,Ti)(17) and alpha- Fe phases are obtained. The optimum conditions are: for R=Nd the samples sp un with a velocity of 30 m s(-1) and annealed at 1373 K for 25 min contain Nd-3(Fe,Ti)(29) as a main phase, 67 wt.%, with some Nd(Fe,Ti)(12) and alpha -Fe; for R=Pr the samples spun with a velocity of 20 m s(-1) and annealed a t 1323 K for 25 min contain 88 wt.% Pr-3(Fe,Ti)(29) with some Pr-2(Fe,Ti)(1 7) and alpha-Fe. These samples present Curie temperatures typical for the N d-3(Fe,Ti)(29) and Pr-3(Fe,Ti)(29) compounds. The room-temperature saturati on magnetization is 124.2 and 138.7 A m(2) kg(-1) for R=Nd and 135.0 and 11 8.9 A m(2) kg(-1) for R=Pr, before and after annealing, respectively. The a nnealed ribbons show grain sizes of <1 mu m, and a mean stoichiometry of Nd 3Fe24Ti5 and Pr3Fe26.5Ti2.5 for the 3:29 phase. The annealed samples presen t low coercivity values attributed to the presence of the soft alpha-Fe pha se. (C) 1999 Elsevier Science S.A. All rights reserved.