Synthesis and Magnetostrictive Properties of High-Pr Content  ${\rm Sm}_{1-x}{\rm Pr}_{x}{\rm Fe}_{1.9}$ Cubic Laves Alloys
Polycrystalline Sm<sub>1-</sub><i>x</i>Pr<i>x</i>Fe<sub>1.9</sub> (0.4 ≤ <i>x</i> ≤ 1.0) magnetostrictive alloys were synthesized by arc-melting and subsequent high-pressure annealing. Measurements of x-ray diffraction, magnetization, and magnetostriction were performed on the alloys. Due to the effects of high-pressure, the alloys are stabilized in cubic Laves phase with MgCu<sub>2</sub>-type structure. The Curie temperature of the cubic Laves phase decreases linearly with the increase of <i>x</i>, which can be associated with the decreasing strength of 3<i>d</i>-4<i>f</i> coupling. With increasing <i>x</i> , the anisotropy of the alloys first decreases to a minimum at <i>x</i> = 0.6 and then increases. The magnetostriction of Sm<sub>1-</sub><i>x</i>Pr<i>x</i>Fe<sub>1.9</sub> changes signs from negative into a positive at <i>x</i> = 0.6 . The saturation magnetostriction increases with increasing <i>x</i>, while the sample with <i>x</i> = 0.9 shows a peak at low magnetic fields.
Structure and magnetostriction of Sm1−xPrxFe2 and Sm0.9Pr0.1(Fe1−yBy)2 alloys
The structure, magnetostriction and anisotropy of Sm1-xPrxFe2 and Sm0.9Pr0.1(Fe1-yBy)(2) alloys have been investigated using X-ray diffraction, standard strain gauge technique and Mossbauer spectrum. It is found that the matrix of homogenized Sm1-xPrxFe2 alloys is the (Sm,Pr)Fe-2 phase with MgCu2-type cubic structure and the minor phases are (Sm,Pr)Fe-3 phase and rare earth-rich phase when x less than or equal to 0.3. When x = 0.4, the (Sm,Pr)Fe-3 phase is found to be the main phase and the minor phases become (Sm,Pr)Fe-2, (Sm,Pr)(2)Fe-17 and rare earth-rich phase. With further increasing Pr content, the amount of minor phases, (Sm,Pr)(2)Fe-17 and rare earth-rich phase increase, but that of (Sm,Pr)Fe-2 remains almost unchanged. For Sm0.9Pr0.1(Fe1-yBy)(2) alloys, the (Sm,Pr)(Fe,B)(2) as a matrix is up to y = 0.2, and the small amount of second phase is a rare earth-rich phase when y > 0.05. The manetostriction of Sm1-xPrxFe2 alloys exhibits a peak near x = 0.1 and that of Sm0.9Pr0.1(Fe1-yBy)(2) alloys decreases with increasing B content. The Mossbauer spectrum analysis shows that the easy axis of magnetization for Sm1-xPrxFe2 alloys lies in the direction up to x = 0.3 and the anisotropy of Sm1-xPrxFe2 alloys decreases with increasing Pr content. (C) 2002 Elsevier Science B.V. All rights reserved.
Microstructure and magnetostriction of (Dy0.7Tb0.3)1−xPrxFe1.85 and (Dy0.7Tb0.3)0.7Pr0.3Fey alloys
The structure, Curie temperature, and magnetostriction of R(1-x)Pr(x)Fe(1.85) and R(0.7)Pr(0.3)Fe(y) (R = Dy0.7Tb0.3, x less than or equal to 0.5, 1.55 less than or equal to y less than or equal to 1.85) alloys were investigated. The matrix of R(1-x)Pr(x)Fe(1.85) alloys is the MgCu2-type cubic (Dy,Tb,Pr) Fe-2 and the second phase was found to be (Dy,Tb,Pr) Fe-3 when x less than or equal to 0.3. When x>0.4, (Dy,Tb,Pr) Fe-3 is the main phase with the PuNi3-type structure and (Dy,Tb,Pr) Fe-2 becomes the minority phase. In the range of 0.3 1.55, which increased with increasing y. When y = 1.55, the alloy is essentially single phase with the MgCu2-type cubic structure. The lattice parameter of (Dy,Tb,Pr) Fe-2 compound for R(1-x)Pr(x)Fe(1.85) alloys increases slowly with increasing x when x less than or equal to 0.3, and sharply increases when x>0.3. The Curie temperature of the alloys decreases steadily with increasing Pr content. The magnetostrictions of R(1-x)Pr(x)Fe(1.85) and R(0.7)Pr(0.3)Fe(y) alloys decrease with increasing Pr content and Fe content, respectively. The largest magnetostriction at room temperature was found in the alloy R(0.7)Pr(0.3)Fe(1.55) (1480 x 10(-6) at H = 796 kA/m). (C) 1996 American Institute of Physics.