Accession Number:

ADA064671

Title:

Permeability, Magnetomechanical Coupling and Magnetostriction in Grain-Oriented Rare Earth-Iron Alloys,

Descriptive Note:

Corporate Author:

NAVAL SURFACE WEAPONS CENTER WHITE OAK LAB SILVER SPRING MD

Personal Author(s):

Report Date:

1978-11-01

Pagination or Media Count:

17.0

Abstract:

Grain-oriented samples of highly magnetostrictive rare earth-iron compounds have successfully been prepared. These samples possess lower inhomogeneous strains than found in the random polycrystalline RFe2 compounds, resulting in much higher values of relative permeability mu sub r and magnetomechanical coupling k33. A partially oriented Tb 20Dy22ho.58Fe1.95 sample was prepared using a pyrolytic Bridgman type boron nitride crucible. At a bias field of 100 Oe k33 .73, which is considerably larger than found in the random polycrystal of the same composition. A relative permeability of 36 occurs in this same sample when a low ac drive of 1.6 Oe rms is used. A second fabrication method using a horizontal zone technique with a supporting cold finger was employed to grow the ternary Tb27Dy.73Fe1.98. The low ac drive values of k33 and Mu sub r were .74 and 19 respectively. The permeability at low bias was found to possess a sharp ac drive dependence. Near zero bias, when the drive was changed from 1.6 Oe rms to 13 Oe rms, mu sub r in the quaternary increased from 36 to 98. In the ternary the values of mu sub r near zero bias increased from 19 to 61. Magnetostriction measurements on both samples show a significant increase in d lambda and gamma s over the random Polycrystals. Author

Subject Categories:

  • Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE