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Title: Comparison of microstructure and magnetic properties of gas-atomized and melt-spun MRE-Fe-Co-M-B (MRE=Y+Dy+Nd,M=Zr+TiC)

Abstract

An MRE{sub 2}(Fe,Co){sub 14}B alloy with Zr substitution and TiC addition was systematically studied. It was found by means of X-ray diffraction, transmission electron microscopy (TEM) and magnetic measurements that the combination of Zr substitution and TiC addition yields adequate microstructural control in both gas atomization (GA) and melt spinning (MS) techniques. For MS ribbons, an H{sub cj} of 11.7 kOe and (BH){sub max} of 11.9 MGOe at 27 degree sign C were obtained in the ribbons spun at 16 m/s and annealed at 700 degree sign C for 15 min. For GA powders, an H{sub cj} of 9.1 kOe and (BH){sub max} of 9.2 MGOe at 27 degree sign C were obtained in 20-25 {mu}m GA powder annealed at 700 degree sign C for 15 min. The temperature coefficients of B{sub r} and H{sub cj} are 0.06 and 0.36%/ degree sign C for the MS ribbon and 0.09 and 0.4%/ degree sign C for the GA powder in the temperature range of 27-100 degree sign C, respectively. TEM images revealed that the MS ribbon consists of a fine and uniform microstructure with an average size of 30 nm, while the GA spherical powder consists of an interior coarsened microstructuremore » with a grain size of 80 nm and a rim area with a grain size of 10 nm.« less

Authors:
; ; ; ; ;  [1]
  1. Ames Laboratory of USDOE, Iowa State University, Ames, Iowa 50011 (United States)
Publication Date:
OSTI Identifier:
20982865
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 9; Conference: 10. joint MMM/INTERMAG conference, Baltimore, MD (United States), 7-11 Jan 2007; Other Information: DOI: 10.1063/1.2710551; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; ATOMIZATION; BORON ALLOYS; COBALT ALLOYS; DYSPROSIUM ALLOYS; FERROMAGNETIC MATERIALS; GRAIN SIZE; IRON ALLOYS; MAGNETIC PROPERTIES; NEODYMIUM ALLOYS; POWDERS; TEMPERATURE COEFFICIENT; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0013-0065 K; TEMPERATURE RANGE 0065-0273 K; TITANIUM CARBIDES; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; YTTRIUM ALLOYS; ZIRCONIUM ALLOYS

Citation Formats

Tang, W., Wu, Y. Q., Dennis, K. W., Kramer, M. J., Anderson, I. E., and McCallum, R. W. Comparison of microstructure and magnetic properties of gas-atomized and melt-spun MRE-Fe-Co-M-B (MRE=Y+Dy+Nd,M=Zr+TiC). United States: N. p., 2007. Web. doi:10.1063/1.2710551.
Tang, W., Wu, Y. Q., Dennis, K. W., Kramer, M. J., Anderson, I. E., & McCallum, R. W. Comparison of microstructure and magnetic properties of gas-atomized and melt-spun MRE-Fe-Co-M-B (MRE=Y+Dy+Nd,M=Zr+TiC). United States. doi:10.1063/1.2710551.
Tang, W., Wu, Y. Q., Dennis, K. W., Kramer, M. J., Anderson, I. E., and McCallum, R. W. Tue . "Comparison of microstructure and magnetic properties of gas-atomized and melt-spun MRE-Fe-Co-M-B (MRE=Y+Dy+Nd,M=Zr+TiC)". United States. doi:10.1063/1.2710551.
@article{osti_20982865,
title = {Comparison of microstructure and magnetic properties of gas-atomized and melt-spun MRE-Fe-Co-M-B (MRE=Y+Dy+Nd,M=Zr+TiC)},
author = {Tang, W. and Wu, Y. Q. and Dennis, K. W. and Kramer, M. J. and Anderson, I. E. and McCallum, R. W.},
abstractNote = {An MRE{sub 2}(Fe,Co){sub 14}B alloy with Zr substitution and TiC addition was systematically studied. It was found by means of X-ray diffraction, transmission electron microscopy (TEM) and magnetic measurements that the combination of Zr substitution and TiC addition yields adequate microstructural control in both gas atomization (GA) and melt spinning (MS) techniques. For MS ribbons, an H{sub cj} of 11.7 kOe and (BH){sub max} of 11.9 MGOe at 27 degree sign C were obtained in the ribbons spun at 16 m/s and annealed at 700 degree sign C for 15 min. For GA powders, an H{sub cj} of 9.1 kOe and (BH){sub max} of 9.2 MGOe at 27 degree sign C were obtained in 20-25 {mu}m GA powder annealed at 700 degree sign C for 15 min. The temperature coefficients of B{sub r} and H{sub cj} are 0.06 and 0.36%/ degree sign C for the MS ribbon and 0.09 and 0.4%/ degree sign C for the GA powder in the temperature range of 27-100 degree sign C, respectively. TEM images revealed that the MS ribbon consists of a fine and uniform microstructure with an average size of 30 nm, while the GA spherical powder consists of an interior coarsened microstructure with a grain size of 80 nm and a rim area with a grain size of 10 nm.},
doi = {10.1063/1.2710551},
journal = {Journal of Applied Physics},
number = 9,
volume = 101,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • Effects of a TiC addition on microstructure and magnetic properties in [MRE{sub 2.2}Fe{sub 14}B]{sub (100-2x)/17.2}+Ti{sub x}C{sub x}(MRE=Nd+Y+Dy,x=1-5) ribbons, melt spun at a wheel speed of 16 m/s, were systematically studied. X-ray diffraction and differential thermal analysis data revealed that the addition of TiC improves the glass formability in the mixed rare earth alloys without Co, resulting in partially amorphous alloys. TEM observations showed that the average grain size in the as spun samples decreases from 200 to 20 nm with increasing x from 1 to 5, confirming that the addition of TiC can significantly improve microstructure. For an optimized [MRE{submore » 2}(Fe,Co){sub 14}B]{sub (100-2x)/17.2}+Ti{sub x}C{sub x} sample with x=2, spun at 25 m/s and annealed at 750 deg. C for 15 min, the room-temperature magnetic properties of H{sub cj}=11.8 kOe, M{sub r}=7.2 kGs, and (BH){sub max}=11.3 MGOe were obtained. Temperature coefficients for M{sub r} and H{sub cj} of -0.06 and -0.37%/ deg. C, respectively, also were measured in the temperature range of 27-100 deg. C. The new magnet alloy exhibits more uniform magnetic properties and a usable energy product to nearly 300 deg. C.« less
  • Gas atomization powder with Zr substitutions for the MRE and ZrC additions were systematically studied. The results show that the partial substitutions of Zr and the ZrC additions effectively improved glass formability in the alloys. Scanning electron microscopy (SEM) revealed that the as-atomized powder with a particle size of less than 32 {micro}m is predominately uniform equiaxed grains with an average grain size of 1.5 {micro}m. X-ray diffraction and differential thermal analysis measurements detected very tiny amounts of amorphous phase. After annealing at 700 C for 15 min, the SEM grain microstructure exhibits a minor change, but magnetic properties aremore » substantially improved. M versus T measurements reveal that the phase composition evolved from 2:14:1 plus a small amount of 2:17 phases to a single 2:14:1 phase during the annealing process. The sieve analysis of the powders showed a particle size distribution with 90 wt % of the powder less than 45 {micro}m. The magnetic properties of the annealed powder varied with particle size. (BH){sub max} first increases with increasing particle size from 5 {micro}m, reaches the peak value in the size range of 20-25 {micro}m, and then decreases with increasing particle size. For the 20-25 {micro}m powder sample annealed at 700 C for 15 min, the (BH){sub max} of 9.6 MG Oe at room temperature and 5.6 MG Oe at 200 C were obtained, respectively.« less
  • Rapidly solidified samples of Nd{sub 9.5}Fe{sub 84.5}B{sub 6} with and without 3 at.{percent} TiC were prepared by melt spinning and melt extraction and then annealed in vacuum (3{times}10{sup {minus}6} Torr) at temperatures from 600 to 750{degree}C. For alloys melt spun under similar conditions, the overquenched state was achieved at wheel speeds {gt}10 m/s for the TiC added alloy while {gt}20 m/s was necessary without TiC. The overquenched samples contained a smaller fraction of {alpha}-Fe in smaller grains than the undercooled samples where Fe dendrites formed near the free surface during solidification. These Fe dendrites were not removed by annealing. Inmore » addition, large orientated 2-14-1 grains nucleated on the Fe dendrites. This combination is detrimental to the magnetic properties. The addition of TiC results in improved control of the microstructure over a larger fraction of the ribbon volume enhancing the magnetic properties. {copyright} {ital 1998 American Institute of Physics.}« less
  • The magnetic and microstructural properties of melt-spun Nd{sub 18}Fe{sub 76{minus}X}Ga{sub X}B{sub 6} alloys have been studied as a function of Ga content. Coercivities of 17 kOe were obtained in underquenched samples having a large grain size of 500 nm. Samples prepared at wheel speeds of 15--19 m/sec, as well as overquenched (40 m/sec) and subsequently annealed, gave coercivities of around 20 kOe with no significant improvement of H{sub c} upon Ga substitution. In Ga-free samples prepared by annealing highly overquenched ribbons (at 60 m/sec) only moderate coercive fields could be achieved (14 kOe). These samples had grain sizes of 70--100more » nm. However Ga substituted samples prepared under the same conditions have a fine grain structure consisting of unequiaxed grains with size around 20 nm and show coercivities up to 23 kOe.« less
  • Melt-spun ribbons of Nd-Fe-Co-B-C system alloys were prepared by the single roller rapid-quenching method. The effects of composition, substrate surface velocity, and heat treatment on the magnetic properties were studied. A maximum energy product of 140.5 kJ/m{sup 3} was obtained for Nd{sub 11}Fe{sub 72}Co{sub 8}(B{sub 0.5}C{sub 0.5}){sub 9} alloy ribbon prepared at a substrate surface velocity of 17.1 m/s. The amorphous Nd{sub 11}Fe{sub 72}Co{sub 8}(B{sub 0.5}C{sub 0.5}){sub 9} ribbons prepared at a substrate surface velocity of 20.7 m/s were crystallized by heat treatment, and the optimum annealing condition was found to be at 600 {degree}C for 30 min. Then themore » value of ({ital BH}){sub max} was 138.5 kJ/m{sup 3}. The value of ({ital BH}){sub max} for a Nd{sub 11}Fe{sub 72}Co{sub 8}(B{sub 0.5}C{sub 0.5}){sub 9} bonded magnet prepared by using the ribbons heated at 600 {degree}C was 90.4 kJ/m{sup 3}.« less