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Magnetostrictive materials and method for improving AC characteristics in same

United States Patent

August 14, 2001
View the Complete Patent at the US Patent & Trademark Office
Ames Laboratory - Visit the Iowa State University Research Foundation - Office of Intellectual Property & Technology Transfer Website
The present invention provides Terfenol-D alloys ("doped" Terfenol) having optimized performances under the condition of time-dependent magnetic fields. In one embodiment, performance is optimized by lowering the conductivity of Terfenol, thereby improving the frequency response. This can be achieved through addition of Group III or IV elements, such as Si and Al. Addition of these types of elements provides scattering sites for conduction electrons, thereby increasing resistivity by 125% which leads to an average increase in penetration depth of 80% at 1 kHz and an increase in energy conversion efficiency of 55%. The permeability of doped Terfenol remains constant over a wider frequency range as compared with undoped Terfenol. These results demonstrate that adding impurities, such as Si and Al, are effective in improving the ac characteristics of Terfenol. A magnetoelastic Gruneisen parameter,, has also been derived from the thermodynamic equations of state, and provides another means by which to characterize the coupling efficiency in magnetostrictive materials on a more fundamental basis.
Pulvirenti; Patricia P. (Chicago, IL), Jiles; David C. (Ames, IA)
Iowa State University Research Foundation, Inc. (Ames, IA)
08/ 953,192
October 17, 1997
STATEMENT OF GOVERNMENT RIGHTS This invention was made with support of the United States Government under United States Department of Energy Contract No. W-7405-ENG-82. The Government has certain rights in this invention.