Electromechanical coupling coefficient (K₃₃) of Fe₈₁Ga₁₉ magnetostrictive alloy

Fe₈₁Ga₁₉ magnetostrictive oriented crystalline has been prepared by zone melting unidirectional solidification. Vacuum annealing at 900°C for 3 h has been carried out followed by oil quenching. The electromechanical coupling coefficient (K₃₃) was determined by the impedance resonance frequency test. When the DC magnetic field intensities increased from 32.7 mT to 48.1 and 63.6 mT, the K₃₃ values increased from 0.126 to 0.129 and 0.133, respectively. With the increase of pressure from 0 to 15 MPa, K₃₃ remains unchanged at 32.7 mT, but at 63.6 mT and 15 MPa K₃₃ of the heat treated sample is increased to 0.157. Surface quality of sample affects the AC impedance curve and it is hard to measure the K₃₃ of defective sample.