Structure and magnetostriction of PrxDy1−xFe2 and Pr0.4Dy0.6(Fe1−yMy)2 alloys (M=Co, Ni)

Abstract

The structure, Curie temperature and magnetostriction of PrxDy1−xFe2 (0⩽x⩽0.5) and Pr0.4Dy0.6(Fe1−yMy)2 (0⩽y⩽0.6) alloys (M=Co, Ni) have been investigated using optical microscopy, x-ray diffraction, ac initial susceptibility and standard strain gauge techniques. The matrix of homogenized PrxDy1−xFe2 alloys is a cubic Laves phase (Pr, Dy)Fe2 with MgCu2-type structure, with a small amount of second phase (Pr, Dy)Fe3 when x⩽0.2. The amount of (Pr, Dy)Fe3 phase increases with the increase of Pr content, and it becomes the main phase when x=0.4. When x=0.5, the matrix is found to be the (Pr, Dy)2Fe17 phase coexisting with a small amount of phases (Pr, Dy)Fe2, (Pr, Dy)Fe3 and rare-earth rich phases. For Pr0.4Dy0.6(Fe1−yCoy)2 alloys, the amount of (Pr, Dy)(Fe, Co)2 phase increases with increasing Co content and the phase (Pr, Dy)(Fe, Co)2 becomes the main phase when y=0.6. However, the substitution of Ni for Fe up to 60 at % Ni in Pr0.4Dy0.6Fe2 alloys does not favor the formation of the cubic Laves phase (Pr, Dy)(Fe, Ni)2. The lattice constant of PrxDy1−xFe2 alloys decreases with increasing x, whereas the Curie temperature Tc increases. The magnetostriction of PrxDy1−xFe2 alloys at room temperature exhibits a peak at x=0.3. The lattice constant of Dy0.6Pr0.4(Fe1−yCoy)2 alloys decreases slowly with increasing y; Tc shows a peak when y=0.45, and the room temperature magnetostriction becomes negative when x>0.45. The Curie temperature of Dy0.6Pr0.4(Fe1−yNiy)2 alloys decreses with the increase of Ni content. The room temperature magnetostriction of Dy0.6Pr0.4(Fe1−yNiy)2 also becomes negative when x>0.45.

Magnetic and magnetostrictive properties in high-pressure synthesized Dy1−xPrxFe1.9(0≤x≤1) cubic Laves alloys

“…rearearth phases. In comparison with the structure of Dy 1−x Pr x Fe 2 [7] and Dy 1−x Pr x (Fe 0.9 B 0.1 ) 2 [8] alloys with high-Pr content prepared by normal-pressure annealing, our samples are free of RE 2 Fe 17 or REFe 3 phase. Generally, the atomic size plays an important role in the formation REFe 2 cubic Laves alloys.…”

“…However, former studies showed that the alloy with cubic Laves phase is difficult to be synthesized under normal pressure when the concentration of Pr is high. For example, Wang et al investigated the structure and magnetostriction of normal-pressure annealed Dy 1−x Pr x Fe 2 alloys [7]. It was found that (Pr,Dy)Fe 2 cubic Laves phase is the main phase of the alloy with x ≤ 0.2.…”

Magnetostriction of 〈110〉 oriented crystals in Tb0.36Dy0.64(Fe1−xCox)2 (x = 0–0.30) alloys

“…This indicates that the addition of Co decreases the amount of rare-earth rich phase. In another word, the Co addition is beneficial for the formation of the Laves phase, similar as in the Pr 0.4 Dy 0.6 (Fe 1−x Co x ) 2 [14] and Tb 0.2 Pr 0.8 (Fe 1−x Co x ) 2 systems [15]. with increasing the temperature.…”

Structural, magnetic, and magnetostrictive properties of Laves (Tb0.3Dy0.7)1−xPrxFe1.55 (0≤x≤0.4) alloys

“…For instance, the success synthesis of single Laves Pr 1−x R x Fe 2 (R = Sm, Tb) alloys was reported with the Pr concentration being restricted to 0.35 for Sm and 0.2 for Tb in order to avoid the appearance of impurity phases [6,7]. Accordingly, much attention has been paid to the stabilized (R, Pr)Fe 2 alloys having relatively high Pr contents in the recent years [8][9][10][11][12][13][14][15]. The partial substitution of Co for Fe was found to stabilize the single Laves phase with a high Pr content of 0.8 in the Pr x Dy 1−x (Fe 0.6 Co 0.4 ) 2 ribbons [10].…”