Microstructure and magnetostrictive properties of Tb–Dy–Fe (Al) alloys

Well-aligned pseudosingle crystals of a series of Terfenol-D and Al-substituted alloys have been prepared using the Czochralski method, a route that has the advantage that a grain-aligned rod can be prepared in one relatively speedy operation. The effects of several factors, including pulling rate, heat treatment, and start material purity, on the magnetomechanical coupling coefficients (k33) of the samples have been investigated. The growth rates mainly influence the drive field to reach its maximum k33, while increasing the start material purity gives a 15% improvement of k33 for the Terfenol-D materials. Studies of Al substitution for Fe in Terfenol-D have also been carried out to see whether the substitution would improve the mechanical properties without significantly altering the magnetostrictive properties.