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

Volume

28

Issue

5

fYear

1992

fDate

9/1/1992 12:00:00 AM

Firstpage

2142

Lastpage

2144

Abstract

Sintered permanent magnets were produced from an Nd₁₇-Fe_76.5-B₅-Cu_1.5 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 H_cj=950 kA/m, B_r=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 Nd₃₀Fe₆₅Cu₅ 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; Nd₁₇Fe_76.5B₅Cu_1.5; 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;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.179423

Filename

179423