Microstructure and magnetostriction of (Dy0.7Tb0.3)1−xPrxFe1.85 and (Dy0.7Tb0.3)0.7Pr0.3Fey alloys

Abstract

The structure, Curie temperature, and magnetostriction of R1−xPrxFe1.85 and R0.7Pr0.3Fey (R=Dy0.7Tb0.3, x≤0.5, 1.55≤y≤1.85) alloys were investigated. The matrix of R1−xPrxFe1.85 alloys is the MgCu2-type cubic (Dy,Tb,Pr) Fe2 and the second phase was found to be (Dy,Tb,Pr) Fe3 when x≤0.3. When x>0.4, (Dy,Tb,Pr)Fe3 is the main phase with the PuNi3-type structure and (Dy,Tb,Pr) Fe2 becomes the minority phase. In the range of 0.3<x≤0.4, both MgCu2- and PuNi3-type structures coexist. The R0.7Pr0.3Fey alloys contain a small amount of (Dy,Tb,Pr) Fe3 phase when y>1.55, which increases 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)Fe2 compound for R1−xPrxFe1.85 alloys increases slowly with increasing x when x≤0.3, and sharply increases when x>0.3. The Curie temperature of the alloys decreases steadily with increasing Pr content. The magnetostrictions of R1−xPrxFe1.85 and R0.7Pr0.3Fey alloys decrease with increasing Pr content and Fe content, respectively. The largest magnetostriction at room temperature was found in the alloy R0.7Pr0.3Fe1.55 (1480×10−6 at H=796 kA/m).