Isotropic bulk exchange-spring magnets with 34 kJ/m/sup 3/ prepared by spark plasma sintering method

Autor: N. Waki, M. Shimada, H. Ono, M. Tani, P. Yamamoto, T. Sugiyama, Akira Fujiki
Rok vydání: 2001
Předmět:
Zdroj: IEEE Transactions on Magnetics. 37:2552-2554
ISSN: 0018-9464
DOI: 10.1109/20.951232
Popis: Densification of exchange-spring magnet ribbons of Nd/sub x/Fe/sub 85-x/Co/sub 8/V/sub 1/B/sub 6/ (x=7-11) alloys has been investigated. The starting ribbon powders containing amorphous parts were prepared by melt spinning and were compacted by using a spark plasma sintering (SPS) method. SPS is a type of solid compression sintering similar to hot-pressing and the sintering promotion factor is self-heat generation by electric discharges between particles when the on-off DC pulse is applied. The bulk magnets indicated the springback phenomenon, pointing to multiple phases of the Nd/sub 2/Fe/sub 14/B type and the /spl alpha/-Fe type, and had isotropic magnetic properties. With increasing Nd content, B/sub r/ decreased from 1.05 T to 0.82 T and H/sub cJ/ increased from 256 kA/m to 832 kA/m. These changes were equivalent to those of the starting ribbons following annealing. The grain sizes of these bulk magnets were about 40 nm when x=7-11. Under optimum preparation conditions, bulk Nd/sub 10/Fe/sub 75/Co/sub 8/V/sub 1/B/sub 6/ magnet indicated (BH)/sub max/=134 kJ/m/sup 3/ (16.8 MGOe).
Databáze: OpenAIRE