STRESS EFFECT ON THE MAGNETIZATION OF DY IN THE DY DYFE2 EUTECTIC/

The magnetization of the alloy DyFe1.5 was studied as a function of te mperature from 50 to 300 K in a range of magnetic field up to 10 kOe. Metallographic studies showed the existence of a eutectic phase contai ning both DyFe2 and elemental Dy embedded in the DyFe2 matrix. The pre sence of elemental By was observed in the magnetization data through a cusp in the temperature dependence of the magnetization at 178 K and an increase of the magnetization starting at 130 K and continuing to 8 0 K. While the first feature occurs at precisely the Neel temperature of bulk Dy, the second contrasts with the jump at the Curie temperatur e of 89 K observed in low fields in bulk single-crystal Dy. The more g radual increase in magnetization observed in the DyFe1.5 alloy is attr ibuted to variations in stress to which the By is subjected. The tempe rature dependence of the magnetic moment from 80 to 130 K is modeled a s arising from a collection of Dy particles of varying Curie temperatu res. This variation is in turn caused by the stress distribution. Curi e temperature distributions are found for a range of magnetic fields a nd then are extrapolated to zero field in order to eliminate the effec t of field. The calculations indicate that a significant amount of the Dy remains in the helimagnetic phase down to zero temperature.