Study On Preparation Process And Properties Of Rare-Earth Magnetostrictive Materials

In this paper, the Giant Magnetostrictive Materials have been fabricated with arc-melting and melt-spun methods. Structure, magnetic properties and magnetostriction have been investigated with XRD, a.c. susceptibility, Vibrating Sample Magnetometer, Scanning Electron Microscopy and standard strain gauge techniques.Tb0.27Dy0.73Fex (x=1.7-2.0) melt-spun ribbons are fabricated by the single-roll technique. All the ribbons are the MgCu2-type phase at the wheel speed of 45 ms-1. For Tb0.27Dy0.73Fex alloy, the high wheel speed is beneficial to eliminate the RFe3 phase and form the perfect MgCu2-type phase. Compared with the bulk of Tb0.27Dy0.73Fex alloy, the ribbons exhibit larger intrinsic coercivity (Hci) and saturation magnetization (Ms). The grain size of these ribbons is reduced with increase of the wheel surface speed. For Tb0.27Dy0.73Fe1.95 melt-spun ribbons, the (440) peak of these ribbons do not exhibit obvious split which are different from that of the bulk compound.Study on PrxTb0.3Dy0.7-xFe2 alloys shows the effect of Pr substitution for Dy. With the increasing of Pr substitution for Dy, the second phase increases. It shows good result when x=0.1 and x=0.15. Pr0.15Tb0.3Dy0.55Fe2 alloy exhibits the largest magnetostriction in PrxTb0.3Dy0.7-xFe2 alloys and the magnetostriction of Pr0.1Tb0.3Dy0.6 Fe2 alloy saturates at low magnetic field which is benefit for application. When x>0.2, the second phase in PrxTb1-xFe1.9 alloy appears. The second phase mainly is DyFe3. But the amount of rich rare earth increases with the increasing of Pr substitution for Tb. When x≤0.2, the change of lattice parameter is agree with the Vegard Law with the increasing of Pr substitution for Tb. This substitution is just atom substitution, there is no essential change. The result of electron probe analysis shows that Pr concentration in Laves phase for arc-melt Pr0.3Tb0.7Fe2 alloys is 0.23. The substitution of Pr for Tb has no effect on the intrinsic magnetostrictionλ111. The addition of boron atom in PrxTb1-xFe2 can effectively prevent the non-cubic phases. We fabricated high Pr concentration of Pr0.3Tb0.7Fe1.9Bx ribbons by melt-spun method and proper heat treatment.