MICROSTRUCTURE AND MAGNETOSTRICTION OF (DY0.7TB0.3)(1-X)PR(X)FE(1.85)AND (DY0.7TB0.3)(0.7)PR0.3FEY ALLOYS

The structure, Curie temperature, and magnetostriction of R(1-x)Pr(x)F e(1.85) and R(0.7)Pr(0.3)Fe(y) (R = Dy0.7Tb0.3, x less than or equal t o 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 Mg Cu2-type cubic (Dy,Tb,Pr) Fe-2 and the second phase was found to be (D y,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) F e-2 becomes the minority phase. In the range of 0.3<x less than or equ al to 0.4, both MgCu2- and PuNi3-type structures coexist. The R(0.7)Pr (0.3)Fe(y) alloys contain a small amount of (Dy,To,Pr) Fe-3 phase when y>1.55, which increased with increasing y. When y = 1.55, the alloy i s essentially single phase with the MgCu2-type cubic structure. The la ttice parameter of (Dy,Tb,Pr) Fe-2 compound for R(1-x)Pr(x)Fe(1.85) al loys 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 all oys decreases steadily with increasing Pr content. The magnetostrictio ns 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 magnet ostriction 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.