The structure, Curie temperature, and magnetostriction of R1−xPrxFe1.85and R0.7Pr0.3Fey(R=Dy0.7Tb0.3,x≤0.5, 1.55≤y≤1.85) alloys were investigated. The matrix of R1−xPrxFe1.85alloys is the MgCu2‐type cubic (Dy,Tb,Pr) Fe2and the second phase was found to be (Dy,Tb,Pr) Fe3whenx≤0.3. Whenx>0.4, (Dy,Tb,Pr)Fe3is the main phase with the PuNi3‐type structure and (Dy,Tb,Pr) Fe2becomes the minority phase. In the range of 0.3<x≤0.4, both MgCu2‐ and PuNi3‐type structures coexist. The R0.7Pr0.3Feyalloys contain a small amount of (Dy,Tb,Pr) Fe3phase wheny>1.55, which increases with increasingy. Wheny=1.55, the alloy is essentially single phase with the MgCu2‐type cubic structure. The lattice parameter of (Dy,Tb,Pr)Fe2compound for R1−xPrxFe1.85alloys increases slowly with increasingxwhenx≤0.3, and sharply increases whenx>0.3. The Curie temperature of the alloys decreases steadily with increasing Pr content. The magnetostrictions of R1−xPrxFe1.85and R0.7Pr0.3Feyalloys decrease with increasing Pr content and Fe content, respectively. The largest magnetostriction at room temperature was found in the alloy R0.7Pr0.3Fe1.55(1480×10−6atH=796 kA/m). ©1996 American Institute of Physics.