Preparation Of Rare Earth (TbDyHo)-Fe Materials And Its Magnetostrictive Properties

The Tb-Dy-Fe alloy has a giant magnetostriction,high energy density,good reliability and fast response characteristics,and has a widely application in the field of sonar,aerospace,robotics and others.It was one of key materials,known as the development of high and new technology in the new century.The Ho element was added on the basis of Tb-Dy-Fe alloy,hoping to obtain large magnetostriction or small hysteresis,and to change the properties of the alloy through heat treatment of high temperature and magnetic field heat treatment.By means of X-ray diffraction,scanning electron microscope,differential thermal analysis,magnetic testing system of multi-parameter and vibrating sample magnetometer,the microstructure,phase transformation and magnetic properties of samples were investigated.The large size bars of Tb_0.26Dy_0.74-xHo_xFe_1.9?x=0.2,0.25?alloys were prepared by the directional solidification technology.For Tb_0.26Dy_0.74-xHo_xFe_1.9 alloys,the saturation magnetostriction was 650 ppm for x=0.2 in the subsurface along the radial,and was 800ppm for x=0.25.The saturation magnetostriction was 1000 ppm for x=0.2 in the middle along the axial,and was 930 ppm for x=0.25.The magnetostrictive properties can be improved by means of magnetic heat treatment and under a pressure.The microstructure and magnetostriction of Tb_0.26Dy_0.74-xHo_xFe_1.9.9 alloys,annealed for 4 hours at 1000 degree,was investigated and the magnetostriction was increased from 57 ppm to 520 ppm at 100kA/m.It was found that the saturation magnetostriction of Tb_0.26Dy_0.74-xHo_xFe_1.9.9 alloys can reach 1012 ppm under 10 MPa pressure.The Tb_0.26Dy_0.74-xHo_x Fe_1.9?x=0.21,0.25,0.31?alloys were prepared by bonding technology.The magnetostriction of annealed Tb_0.26Dy_0.74-xHo_xFe_1.9.9 alloys was investigated.It was found that the magnetostriction can reach an optimum value when x=0.31.The magnetostriction of bonded Tb_0.26Dy_0.43Ho_0.31Fe_1.9.9 alloy was 202 ppm when the magnetic field was 100 kA/m.The saturation magnetostriction?s of the alloy when x=0.31 can reach160 ppm after magnetic annealing at 100?.