The melting diagram of the Ti-Dy-Si system in the Ti-Ti5Si3-Dy5Si3-Dy region

The phase equilibria in the Ti-Ti5Si3-Dy5Si3-Dy part of the Ti-Dy-Si system were studied by DTA, X-ray diffraction, metallography and EPMA. The melting diagram, isopleths at 5Si, 65Ti and 65Dy, and a reaction scheme were constructed. The solidus surface is characterized by the following three-phase fields: <β-Ti> + + , <β-Ti> + + <α-Dy>, + <α-Dy> + , and + + . The first two fields form via U-type equilibria, L + ↔ <β-Ti> + and L + <β-Ti> ↔ + <α-Dy>, at 1320 and 1170 deg. C, respectively. The third three-phase field results from an invariant eutectic four-phase equilibrium, L ↔ + <α-Dy> + , at 1157 ± 6 deg. C. The fourth one is the result of a P-type equilibrium, L + + ↔ . The temperature of the latter was estimated to be within the interval 1650-1700 deg. C