Accession Number : ADA138123

Title :   Studies of Coercive Force of Permanent Magnet Materials.

Descriptive Note : Final rept. 1 Jan-31 Dec 83,


Personal Author(s) : Wallace,W E

PDF Url : ADA138123

Report Date : 31 Jan 1984

Pagination or Media Count : 14

Abstract : Permanent magnets were prepared by sintering on-stoichiometry Sm2Co17 and Sm2Co17 doped Fe,Mn,Zr and Hf. Coercive forces subscript i H subscript C were low, less than 1 kOe. Although doping increases anisotropy field, it does not enhance subscripti H subscript C except for Mn as dopant. In this case, doping increases subscript i H subscript C about two-fold. In these systems subscript i H subscript C seems to be nucleation-controlled. It is postulated that nucleation occurs at the oxidized surface where anisotropy is weak or negative. Surfaces were investigated by Auger spectroscopy with results consistent with the postulated mechanism. To test for effects of surface roughness, powders were washed with acid. No increase in subscript i H subscript C was observed. Samples ground under pentane and liquid nitrogen showed no significant difference in subscript i H subscript C. Oxygen content was about 3000 ppm by weight in the finished magnets. Results suggest that coercive force of the so-called 2-17 magnets (which are actually 2-phase mixtures of components with 1:5 and 2:17 stoichiometry, originates with the component having 1:5 stoichiometry.

Descriptors :   *Permanent magnets, *Magnetic materials, *Coercive force, Sintering, Stoichiometry, Samarium, Cobalt, Doping, Iron, Manganese, Zirconium, Hafnium, Low level, Anisotropy, Nucleation, Control, Surfaces, Auger electron spectroscopy, Surface roughness

Subject Categories : Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE