Microstructual investigation of mixed rar earth iron boron processed vis melt-spinning and high-pressure gas-atomization for isotrophic bonded permanent magnets
- Iowa State Univ., Ames, IA (United States)
A solid solution of three rare earths (RE) in the RE2Fe14B structure have been combined to create the novel mixed rare earth iron boron (MRE2Fe14B) alloy family. MRE2Fe14B exhibits reduced temperature dependent magnetic properties; remanence and coercivity. The desired form of MRE2Fe14B is a powder that can be blended with a polymer binder and compression or injection molded to form an isotropic polymer bonded permanent magnet (PBM). Commercially, Nd2Fe14B is the alloy of choice for PBMs. Powders of Nd2Fe14B are made via melt-spinning as can be MRE2Fe14B which allows for direct comparisons. MRE2Fe14B made using melt-spinning at high wheel speeds is overquenched and must be annealed to an optimal hard magnetic state. Due to the rare earth content in the MRE2Fe14B powders, they must be protected from the environment in which they operate. This protection is accomplished by using a modified fluidized bed process to grow a protective fluoride coating nominally 15nm thick, to reduce air oxidation. MRE2Fe14B has demonstrated reduced temperature dependent magnetic properties in ribbon and PBM form. The real challenge has been modifying alloy designs that were successfully melt-spun to be compatible with high-pressure gas-atomization (HPGA). The cooling rates in HPGA are lower than melt-spinning, as the powders are quenched via convective cooling, compared to melt-spinning, which quenches initially by conductive cooling. Early alloy designs, in gas atomized and melt-spun form, did not have similar phase compositions or microstructures. Alloy additions, such as the addition of zirconium as a nucleation catalyst, were successful in creating similar phases and microstructures in the HPGA powders and melt-spun ribbon of the same MRE2Fe14B composition.
- Research Organization:
- Ames Lab., Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 850076
- Report Number(s):
- IS-T 2562; TRN: US200602%%253
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effect of TiC addition on microstructure and magnetic properties for MRE{sub 2}(Fe,Co){sub 14}B melt-spun ribbons (MRE=Nd+Y+Dy)
Effect of TiC additions to the microstructure and magnetic properties of Nd{sub 9.5}Fe{sub 84.5}B{sub 6} melt-spun ribbons