Title :
Behavior of Nb atoms in Nb substituted Nd2Fe14B nanocrystalline alloys investigated by atom probe tomography
Author :
Wu, Y.Q. ; Kramer, M.J. ; Chen, Z. ; Ma, B.M. ; Miller, M.K.
Author_Institution :
Ames Lab., Iowa State Univ., Ames, IA, USA
fDate :
7/1/2004 12:00:00 AM
Abstract :
The behavior of Nb atoms in Nd12Fe82-xB6Nbx (x=0 to 3) nanocrystalline alloys has been investigated by using atom probe tomography (APT) technique on near-atomic scale in the present paper. Three-dimensional atom probe (3DAP) analyses on the Nb substituted alloys clearly reveal that Nb atoms are enriched at grain boundaries with a peak concentration about 4 times higher than the average for Nd2Fe14B grains. A grain boundary region with a chemical composition near the Nb : Fe : B stoichiometry of 3 : 3 : 5 is also measured for the x=3 alloy. The results provide direct evidence of microstructural refinement due to solute drag of Nb atoms during solidification, resulting in Nb enrichment at grain boundaries and possibly the formation of a Nb-rich interfacial phase which give rise to enhanced magnetic properties.
Keywords :
X-ray diffraction; atom probe field ion microscopy; boron alloys; crystal microstructure; crystallisation; iron alloys; nanostructured materials; neodymium alloys; niobium alloys; solidification; Nb atoms; Nd12Fe82-xB6Nbx; Nd2Fe14B; atom probe tomography; grain boundaries; interfacial phase; magnetic properties; microstructural refinement; nanocrystalline alloys; permanent magnets; solidification; solute drag; Atomic measurements; Grain boundaries; Iron alloys; Laboratories; Magnetic properties; Neodymium; Niobium alloys; Probes; Spatial resolution; Tomography; Atom probe tomography; nanocrystalline; niobium; permanent magnets;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2004.829018
