Structure and magnetostriction of Sm_1-xPr_xFe₂ and Sm_0.9Pr_0.1(Fe_1-yB_y)₂alloys

The structure, previous termmagnetostrictionnext term 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 Mössbauer spectrum. It is found that the matrix of homogenized Sm1−xPrxFe2 alloys is the (Sm,Pr)Fe2 phase with MgCu2-type cubic structure and the minor phases are (Sm,Pr)Fe3 phase and rare earth-rich phase when x less-than-or-equals 0.3. When x=0.4, the (Sm,Pr)Fe3 phase is found to be the main phase and the minor phases become (Sm,Pr)Fe2, (Sm,Pr)2Fe17 and rare earth-rich phase. With further increasing Pr content, the amount of minor phases, (Sm,Pr)2Fe17 and rare earth-rich phase increase, but that of (Sm,Pr)Fe2 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 magnetostriction 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 Mössbauer spectrum analysis shows that the easy axis of magnetization for Sm1−xPrxFe2 alloys lies in the <1 1 1> direction up to x=0.3 and the anisotropy of Sm1−xPrxFe2 alloys decreases with increasing Pr content.