Title :
Solidification, quenching gas and magnetic properties in melt-spun Nd2Fe14B
Author :
Lewis, L.H. ; Collins, S.M. ; Kramer, M.J. ; Lo, C.C.H.
Author_Institution :
Div. of Mater. & Chem. Sci., Brookhaven Nat. Lab., Upton, NY, USA
fDate :
7/1/2001 12:00:00 AM
Abstract :
Magnetic measurement and cross-sectional Magnetic Force Microscopy images were obtained from Nd2Fe14B ribbons melt-quenched at a circumferential wheel speed of 10 m/sec in three different atmospheres: 1 atm Ar, 1 atm He and 1/3 atm He. The striking effects of the quenching gas type upon the microstructure is correlated with room-temperature demagnetization curves that confirm the presence of multiple, yet discontinuous, grain size zones. A model for the rapid solidification of Nd2Fe14B based on consideration of recalescence relative to the peritectic temperature is invoked to explain the experimental results. The recalescence causes breakup of the Nd2Fe14B dendrites formed during the first phase of solidification and results in a layered structure within the ribbon possessing distinct transition regions where the solidification front temperature crosses the peritectic temperature
Keywords :
boron alloys; demagnetisation; dendritic structure; ferromagnetic materials; grain size; iron alloys; magnetic force microscopy; melt spinning; neodymium alloys; permanent magnets; quenching (thermal); rapid solidification; Nd2Fe14B; Nd2Fe14B ribbon; cross-sectional imaging; demagnetization; dendritic structure; grain size; layered structure; magnetic force microscopy; magnetic properties; melt spinning; microstructure; peritectic temperature; permanent magnet; quenching gas; rapid solidification; recalescence; Atmosphere; Helium; Iron; Magnetic force microscopy; Magnetic forces; Magnetic properties; Magnetic variables measurement; Neodymium; Temperature; Wheels;
Journal_Title :
Magnetics, IEEE Transactions on
