The large magnetostrlctive strain, λ, possessed by Terfenol-D, TbxDy1-xFey, has been sustained from the research laboratory to commercial production. Transducer drive elements produced by two methods, free-standing zone melt (FSZM) and modified Bridgman (MB), are available in various sizes and shapes. These processes are briefly described. The FSZM single crystal material has about 20% more strain than does the grain oriented MB material. The effects of heat treatment and stoichiometry on the magnetostriction of these drive elements are reported. The recent price reduction is the result of an extensive evaluation of the raw materials, Tb and Dy obtained from several sources. The purity and therefore the cost of these raw materials are the variables and the product was not acceptable if performance was sacrificed. Improved processing techniques and large volumes will lead to further price reductions. Recently, emphasis has been placed on performance consistency, both end-toend and lot-to-lot, and the results of these efforts to produce matched sets of drivers are reported. The potential uses of these giant magnetostrictive materials remain large. This is evident from the numerous first and second stage prototype devices that have been successfully completed. The commercialization of a device that uses a large volume of Terfenol-D drivers will have a major impact on the current applications activities and we are seeing evidence of this becoming a reality in the near future, especially in the areas of sonar, vibration isolation, high force actuators and linear motors.
KeywordsPermeability Anisotropy Acoustics Sonar Terbium
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