Effect of Heat Treatment on Microstructure and Thermal Stability of Nd–Fe–B Sintered Magnets

Author

Youhao Liu ; Shuai Guo ; Renjie Chen ; Dong Lee ; Aru Yan

Author_Institution

Jiang Province Key Lab. of Magn. Mater. & Applic. Technol., Chinese Acad. of Sci., Ningbo, China

Volume

47

Issue

10

fYear

2011

Firstpage

3270

Lastpage

3272

Abstract

The effect of heat treatment on the microstructure and thermal stability of sintered Nd-Fe-B magnets was investigated. The results show that the microstructure of the magnets was greatly affected by heat treatment. The intrinsic coercivity (H_cj) was increased and the temperature coefficient of coercivity (β) was decreased by heat treatment. As the annealing temperature changes from 500°C to 770°C, H_cj first increases and reaches a maximum, then starts to decrease, but β remains unchanged from 500°C to 680°C and increases rapidly when annealed over 680°C. A magnet with H_cj= 30.55 kOe, β (from 20°C to 200°C) = -0.4079%°C was obtained after annealed at 620°C for 2 h. The relationship between the annealing temperature and magnetic properties was studied.

Keywords

annealing; boron alloys; coercive force; crystal microstructure; iron alloys; neodymium alloys; sintering; thermal stability; Nd₂Fe₁₄B; annealing temperature; heat treatment; intrinsic coercivity; magnetic properties; microstructure; sintered magnets; temperature 20 degC to 200 degC; temperature 500 degC to 770 degC; temperature coefficient; thermal stability; time 2 h; Annealing; Coercive force; Grain boundaries; Magnetic resonance imaging; Microstructure; Thermal stability; Coercive force; heat treatment; microstructure; thermal stability;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.2011.2146239

Filename

6028055