The dynamic magnetostriction of nickel-cobalt alloys

The magnetostrictive properties of binary nickel-cobalt alloys in the range 0-23% cobalt are discussed, with particular reference to the use of these materials for transducers. Measurements, at various polarizing fields, of the electromechanical coupling coefficient, reversible permeability and Young's modulus are described. Various criteria which govern the choice of magnetic materials for ultrasonic transducers are discussed and it is shown that two alloys, containing respectively about 4.4 and 18.4% cobalt, give good performance as transducer materials.