Tb-Dy-Fe超磁致伸缩合金的动态机电耦合系数

Electromechanical coupling coefficient (K_33) of Tb-Dy-Fe giant magnetostrictive alloy

用区熔定向凝固方法制备出成分为Tb_(0．3)Dy_(0．7)Fe_(1．90)的〈110〉和〈112〉取向的超磁致伸缩材料,研究了在900℃真空热处理后材料的动态机电耦合系数．结果表明,定向生长的〈110〉和〈112〉取向样品K_(33)值比铸态有明显的提高；随着磁场的增大,K_(33)值先增大后又逐渐减小；外加压力从0MPa增大到10MPa,K_(33)值逐渐增大；继续增大压力,K_(33)值减小．适当的热处理使K_(33)值明显提高．热处理后样品K_(33)值的提高与样品磁畴结构的改变有关．

The nominal Tb0.3Dy0.7Fe1.90 magnetostrictive material oriented along （110） and （112） have been prepared by zone melting unidirectional solidification. Vacuum annealing at 900 ℃ for 4 or 48 h has been carried out. The electromechanical coupling coefficient （K33） is determined by the impedance resonance frequency tested by using AC impedance instrument. K33 of the samples oriented along〈110〉 and 〈112〉 increases comparatively to the as-cast samples. With the increase of DC magnetic field, K33 increased initially, and then decreased. With the increase of stress from 0 MPa to 10 MPa,K33 increased, but at 15 MPa K33 is reduced. K33 is sharply improved after proper heat treatment, which can be attributed to the change of the magnetic domain configuration after heat treatment.