PHASE-EQUILIBRIA IN THE DY-FE-ND SYSTEM AT 500-DEGREES-C

The Dy-Fe-Nd phase diagram at 500 degrees C was determined with the us e of powder X-ray diffraction (XRD), electron probe microanalysis (EPM A), metallography and DTA. The 500 degrees C isothermal section of thi s ternary system consists of 10 single-phase regions, 17 two-phase reg ions and 8 three-phase regions. No ternary compounds have been found. At 500 degrees C the maximum solid solubilities of Nd in DyFe3 and DyF e2 and that of Fe in alpha-Nd(Dy) are about 1 at.%, 3 at.% and 0.1 at. %, respectively. The existence of the metastable phase NdFe2 and delta phase of the Dy-Nd binary system are confirmed, but no evidence of th e existence of Nd3Dy2 was found. The metastable phase NdFe2 appears in the phase regions which include the stable phase DyFe2 but was not fo und in the alloys near the composition of NdFe2.