Intensifying development of giant magnetostrictive materials
It was James Joule, back in 1842, who first observed that a sample of nickel changed length when it was magnetised. Upon application of the external magnetic field cobalt, iron and alloys of these materials also change length as much as 50ppm (parts per million). The effect known as magnetostriction found its first practical application during the second world war when magnetostrictive materials where used for locating the echo in SONAR devices. The breakthrough came in the 1960's when the rare earth elements terbium (Tb) and dysprosium (Dy) were found to have as much as four orders of magnitude higher strains than the strains observed in ordinary nickel based alloys. Consequently alloys based on these rare earth elements were found to again exhibit gigantic magnetorestrictrive properties but now at room temperatures and for lower values of the externally applied magnetic field. Since these early days, intense research on materials properties and the growing mechanisms of crystals has resulted in the creation of a variety of materials suitable for many different applications. The current European funded project has strengthened and intensified cooperation and exchange of information among European research institutes and industries involved in this material's technology. ECAMMA, an acronym for the European Concerted Action on giant Magnetorestrictive Materials and Applications, serves as a European forum of experts on magnetorestriction, from materials to applications. The project has prepared and characterised samples of thin magnetorestrictive films and multi-layers and has available in a database the properties of these structures. New magnetostrictive materials have been developed, their properties measured and compared with each other and with piezoelectric materials. The project partners have investigated software tools for simulation of materials and applications and it has been demonstrated that magnetorestrictive actuators are highly suitable for damage detection and vibration control. Aerospace, automotive and paper industries are only a small sample of the possible industrial enterprises that will contact the expert members of ECAMMA for consultation on the suitability of magnetorestrictive materials for potential applications. Research and development support can also be provided through the Internet at ECAMMA's home site.
