The Study On The Synthesis And Properties For Giant Magnetostrictive Materials With Light Rare Earth

In this paper, the synthesis, magnetic properties and magnetostriction of Laves phase compounds containing Ce and Pr are investigated, and the preparation and properities of Terfenol-D composites with resin and low-melting point metal as bond are studied.The study on the magnetostriction of Pr_xTb_1-xFe_1.9, Pr_xTb_1-xFe_1.9B0.2 and Pr_xTb_1-x(Fe_0.6Co_0.4)_1.9 alloys shows that Pr iron really possesses as large magnetostriction as Tb iron, which confirm the conclusion of the single-iron theory in the experiment. The magnetostriction of Pr0.2Tb0.8(Fe_0.6Co_0.4)_1.9 alloys at 900kA/m is 1765ppm. The concentration of Pr in Pr_xTb_1-xFe_1.9 alloys increases from 0.2 to 0.4 by the addition of B as interstitial atom and Co as substitutional atom for Fe.The magnetostriction of Pr_0.15Tb_0.3Dy_0.55Fe_1.9 alloys at 1200kA/m is 1900ppm, which is 300ppm higher than Tb0.27Dy0.73Fe2 alloy. In the study of substitutional atom for Fe in Pr_0.15Tb_0.3Dy_0.55Fe_1.9 alloy, it is found that Mn and B as substitutional atom for Fe improve the magnetostiction, and Pr_0.15Tb_0.3Dy_0.55Fe1.8Mn0.1 alloy possesses large magnetostriction at the low magntic field. In this alloy, a gaint magnteostriction 1100ppm at 3kOe with the applied compressive stress of 4MPa is obtained, and this alloy is of great potentiality for practical use.The specimen with Pr concentration to 0.5 is synthesized in the compound containing Ce, which shows that Ce iron possesses high bonding energy. In the Pr_x(Ce,Tb)_1-xFe_1.9 alloys, it is found that there exists the valence fluctuation of Ce iron, and the results of magnetic measurement show that the saturation magnetization and magnetostriction behave abnormal change with the Ce concentration changing, which is attributed to differernt magnetic structure in the alloys with different Ce concentration.By the study of the influence of the proportion of bond and compaction pressure on the density, resistivity and magnetostriction, the optimum technics with resin and low-melting point metal as bond is determinated. With the resin as bond, the optimum technics is shown: the compaction pressure between 80MPa and 114MPa; the proportion of binder to powders'weight is 4:100, the Terfenol-D composite prepared by this method possesses 800ppm magnetostriction at 900kA/m. With low-melting point as bond, the optimum technics is shown: the proportion of Sn to powders'volume is 10:100, a compaction pressure of 1.0 GPa, and sintering at 250°C for 150 seconds in rapid temperature program furnace, the Terfenol-D composite prepared by this method possesses 550ppm magnetostriction. The resistivity of resin-bonded Terfenol-D composite is 104 larger than the alloys, which greatly improves the application frequency.