RADIATION DAMAGE THRESHOLDS FOR PERMANENT MAGNETS
Abstract
Permanent magnets were irradiated to integrated neutron flux levels from 3.0 x 10 to the 17th to 4.0 x 10 to the 20th power epicadmium n/sq cm. In spite of this relatively high dose, Alnicos II, V and XII showed negligible change in properties whether irradiated at 60 C, 235 C, or 325 C. Cunico I, though affected, showed changes less than a threshold of radiation damage of + or - 10%. Cunife I and 3-1/2 Chromium Steel showed slight improvements in properties. The Barium Ferrites, Silmanal, 36 Cobalt Steel and others exceeded the 10% damage threshold by various amounts which extended up to severe demagnetization. Differentiation between temperature and radiation effects was accomplished by the use of control magnets, and by the 60 C irradiation. Limitations on the use of Alnicos II, V, XII and Cunico I in combined heat and nuclear radiation environments may be imposed by the higher vulnerability of associated soft magnetic circuit components, e.g., pole pieces of soft iron, to radiation damage and by high gamma heating which can occur if a magnetic circuit must be used in a sealed container (for protection from corrosion or other reasons). The Alnicos exhibit the highest resistance to radiation, while the barium ferrites show the least.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 18, 1961
- Accession Number
- AD0262051
Entities
People
- D. I. Gordon
- R. H. Lundsten
- R. S. Sery
Organizations
- Naval Ordnance Laboratory