Title :
Nd-Fe-B-Cu HD-processed sintered magnets: properties and microstructure
Author :
Knoch, K.G. ; Kianvash, A. ; Harris, I.R.
Author_Institution :
Dept. of Pure & Appl. Phys., Trinity Coll., Dublin, Ireland
fDate :
9/1/1992 12:00:00 AM
Abstract :
Sintered permanent magnets were produced from an Nd17-Fe76.5-B5-Cu1.5 alloy by a two-step heat treatment at 1370 K and 870 K following hydrogen decrepitation (HD)-processing. Optimized heat-treatment yielded magnetic properties of Hcj=950 kA/m, Br=1.1 T, and (BH)max=230 kJ/m3. These properties were hardly affected by cooling rates, in contrast to Cu-free magnets. Microstructural observations showed that the homogeneous distribution of a newly found intergranular phase is important for the development of good coercivity. This phase, the composition of which was determined to be Nd30Fe65 Cu5 by TEM and EDX, was shown by differential thermal analysis investigations to form at ≈870 K. Isolated regions of Nd2Fe17 in the as-sintered material were dissolved after heat treatment
Keywords :
X-ray chemical analysis; boron alloys; coercive force; copper alloys; crystal microstructure; ferromagnetic properties of substances; heat treatment; iron alloys; neodymium alloys; permanent magnets; remanence; sintering; thermal analysis; transmission electron microscope examination of materials; 1370 K; 870 K; EDX; Nd17Fe76.5B5Cu1.5; TEM; coercive field; cooling rates; differential thermal analysis; homogeneous distribution; hydrogen decrepitation processing; intergranular phase; magnetic properties; microstructure; remanent magnetisation; sintered permanent magnets; two-step heat treatment; Annealing; Cooling; Electrons; Magnetic analysis; Magnetic materials; Magnetic properties; Magnets; Microstructure; Spectroscopy; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
