Magnetic properties of Sm(Fe,Ti)(7)CxN delta/alpha-Fe nanocomposites

The structure, phase transformation and magnetic properties of SmyFe93-y-zTi2C7N delta (y = 8, 10, 12, 14; z = 0, 3, 5, 7) alloys prepared by mechanical alloying (MA) and nitrogenation have been studied. The main phase in the alloys transforms from Nd2Fe14B-type to TbCu7-type when the Ti content is increased. The magnetic properties of SmyFe93-y-zTizC7 alloys are improved by nitriding, which is sensitive to the nitriding temperature. The hard magnetic properties of the MA SmyFe93-y-zTizC7Ndelta alloys are better than those of the carbon-free counterparts due to the formation of Sm(Fe,Ti)(7)CxNdelta/alpha -Fe nanocomposite. The Sm12Fe74Ti7C7 alloy, annealed at 850 degreesC for 30 min and nitrided at 400 degreesC for 5 h, has the magnetic properties H-i(c) = 38.5 kOe and (BH)(max)=8.84 MGOe. The re-milling process before nitrogenation is beneficial to achieving the magnetic properties of H,=6.87 kOe and (BH)(max)=13.5 MGOe for Sm10Fe76Ti7C7Ndelta alloys. (C) 2001 Elsevier Science BV All rights reserved.