Directional solidification of Co-Cu-R permanent-magnet alloys

Author

Chin, Gilberty ; Green, Martin L. ; Nesbitt, E.A. ; Sherwood, Richard C. ; Wernick, J.H.

Author_Institution

Bell Telephone Laboratories, Inc., Murray Hill, NJ

Volume

8

Issue

1

fYear

1972

fDate

3/1/1972 12:00:00 AM

Firstpage

29

Lastpage

35

Abstract

Co-Fe-Cu-Ce permanent-magnet alloys have been prepared by directional solidification using a modified Bridgman technique. Samples melted at low superheat temperatures ( $\\Delta T \\sim 20\\deg$ C above the melting point of about 1100°C) and solidified at moderate rates (∼2.3 cm/h) resulted in a reasonably homogeneous columnar grain structure with a preferred crystallographic orientation. The $c$ axis is generally aligned within 15° of the growth axis. Increasing the speed of solidification led to a fine-grained structure with no texture, while decreasing the speed led to coarse columnar grains with erratic orientation. A large superheat temperature ( $\\Delta T \\sim 300-400\\deg$ C resulted in a reaction of the liquid with the alumina crucible wall and led to the formation of face-centered cubic Co-rich dendrites. With the modified Bridgman technique, oriented samples 8 cm long and 2.54 cm in diameter have been prepared with good magnetic properties. After annealing at 1000°C followed by aging at 400°C, a Co3.5Fe0.5CuCe alloy exhibited values ofiHc= 7000 Oe, Br= 6100 G, and $(BH)_{\\max } = 9.2$ MG.Oe. A Co3.6Fe0.5Cu0.9Ce alloy exhibited values ofiHc= 6000 Oe, $B_{r} = 6250$ G, aud $(BH)_{\\max } = 9.5$ MG.Oe after similar treatment.

Keywords

Cobalt-rare earth alloys; Rare earth-cobalt alloys; Annealing; Casting; Crystallography; Furnaces; Magnetic anisotropy; Magnetic properties; Perpendicular magnetic anisotropy; Resistance heating; Shape memory alloys; Temperature;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/TMAG.1972.1067257

Filename

1067257