Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measuremen...Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measurement. The samples were single phase with cubic MgCu2- type structure; with the increase of Dy content, Tc decreased from 240 K （TbCo2） to 130 K （DyCo2）, and the maximum magnetic entropy change ｜ △SM,max｜ increased from 3.133 to 8.176 J/kg-K under low magnetic field of 0-2 T. The Arrott plot and the change of ｜△SM,max｜ showed that magnetic phase transition from second order to first order occured with the increase of Dy content between x=-0.6 and 0.8.展开更多
A simplified quasi-static computational model for self-sensing applications of magnetostrictive actuators based on terfenol-D rods is presented. Paths and angle changes in the magnetic moments rotation of Tb0.3Dy0.7Fe...A simplified quasi-static computational model for self-sensing applications of magnetostrictive actuators based on terfenol-D rods is presented. Paths and angle changes in the magnetic moments rotation of Tb0.3Dy0.7Fe2 alloy are studied as functions of compressive stress and magnetic field, and then used to determine the magnetization in its actuation. Then sensing of magnetic induction picked from a driving coil in an actuator is derived. The model is quick and efficient to solve moments rotation and its magnetization. Sensing results of compressive stress and magnetostriction calculated by the model are in good agreement with experiments and will be helpful in the design and control of self-sensing applications in actuators.展开更多
In order to expand the applications of giant magnetostrictive materials in the field of precision positioning, an extreme value model of free energy was established with deflection angle of magnetic domain as the inde...In order to expand the applications of giant magnetostrictive materials in the field of precision positioning, an extreme value model of free energy was established with deflection angle of magnetic domain as the independent variable from the micro-scopic aspect. The model was based on Stoner-Wohlfarth （S-W） model wherein Tb0.3Dy0.7Fe2 alloy was taken as a research object, and the deflection law of magnetization angle of single magnetic domain was studied through drawing the equipotential curves and changing curves of free energy function under different applied stresses and in different magnetic fields. Research results showed that there were three kinds of magnetization angles of single magnetic domain as for Tb0.3Dy0.7Fe2 alloy, namely 35.26o , 90o and 144.74o ; under the action of applied stresses, the magnetization anglesθwere deflected to the direction of 90o for the magnetic domains of 35.26o and 144.74o and the magnetization anglesψ were changed and transited to the direction ofψ=135o for the magnetic domain of 90o ; the magnetic domain was deflected under the action of small magnetic field for magnetic domain of 35.26o ; with the increase of magnetic field intensity, the magnetic domain of 90o had a transition trend to a stationary planar ofψ=ψ0; the magnetic domain of 144.74o had a transition trend to the direction of magnetic domain of 35.26o. These results laid a foundation for the magnetostrictive mechanism and establishment of precision positioning theories of the giant magnetostrictive materials.展开更多
文摘Phase structure and magnetocaloric effect of （Tb1-xDyx）Co2 alloys with x=0, 0.2, 0.4, 0.6, 0.8, and 1.0 were investigated using X-ray diffraction analysis, differential thermal analysis, and magnetization measurement. The samples were single phase with cubic MgCu2- type structure; with the increase of Dy content, Tc decreased from 240 K （TbCo2） to 130 K （DyCo2）, and the maximum magnetic entropy change ｜ △SM,max｜ increased from 3.133 to 8.176 J/kg-K under low magnetic field of 0-2 T. The Arrott plot and the change of ｜△SM,max｜ showed that magnetic phase transition from second order to first order occured with the increase of Dy content between x=-0.6 and 0.8.
基金Project supported by the National Preeminent Youth Foundation(Grant No.51225702)the National Natural Science Foundation of China(Grant No.51177024)
文摘A simplified quasi-static computational model for self-sensing applications of magnetostrictive actuators based on terfenol-D rods is presented. Paths and angle changes in the magnetic moments rotation of Tb0.3Dy0.7Fe2 alloy are studied as functions of compressive stress and magnetic field, and then used to determine the magnetization in its actuation. Then sensing of magnetic induction picked from a driving coil in an actuator is derived. The model is quick and efficient to solve moments rotation and its magnetization. Sensing results of compressive stress and magnetostriction calculated by the model are in good agreement with experiments and will be helpful in the design and control of self-sensing applications in actuators.
基金Project supported by the National Natural Science Foundation of China(51075001,51575002)Chinese Key Technologies Program of Anhui Province(1301022074)
文摘In order to expand the applications of giant magnetostrictive materials in the field of precision positioning, an extreme value model of free energy was established with deflection angle of magnetic domain as the independent variable from the micro-scopic aspect. The model was based on Stoner-Wohlfarth （S-W） model wherein Tb0.3Dy0.7Fe2 alloy was taken as a research object, and the deflection law of magnetization angle of single magnetic domain was studied through drawing the equipotential curves and changing curves of free energy function under different applied stresses and in different magnetic fields. Research results showed that there were three kinds of magnetization angles of single magnetic domain as for Tb0.3Dy0.7Fe2 alloy, namely 35.26o , 90o and 144.74o ; under the action of applied stresses, the magnetization anglesθwere deflected to the direction of 90o for the magnetic domains of 35.26o and 144.74o and the magnetization anglesψ were changed and transited to the direction ofψ=135o for the magnetic domain of 90o ; the magnetic domain was deflected under the action of small magnetic field for magnetic domain of 35.26o ; with the increase of magnetic field intensity, the magnetic domain of 90o had a transition trend to a stationary planar ofψ=ψ0; the magnetic domain of 144.74o had a transition trend to the direction of magnetic domain of 35.26o. These results laid a foundation for the magnetostrictive mechanism and establishment of precision positioning theories of the giant magnetostrictive materials.
