Experimental investigation of phase equilibria in the Ni-Ta-Si refractory alloy system

•The isothermal sections at 1300, 1100 and 900 °C were experimentally determined.•A new ternary compound (named F) was detected within the compositional range of Ni23–25Ta39–40Si35–38.•The range of the ternary Laves phase (C14) was revised to be Ni39–54Ta26–33Si13–27.•The binary NiTa2 and Ta2Si phases form a continuous solid solution (Ni, Si)Ta2. Three isothermal sections of the Ni-Ta-Si ternary system at 1300, 1100 and 900 °C were constructed in the whole composition range and analysed using electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. In addition to the known ternary G, E, H and C14 phases, a new compound with the composition of Ni23–25Ta39–40Si35–38 was detected for the first time, herein designated as the F phase. Furthermore, the continuous (Ni, Si)Ta2 phase was found to be stable and the composition range of the ternary C14 Laves phase was revised to be Ni39–54Ta26–33Si13–27. The newly determined phase equilibria in the Ni-Ta-Si ternary system can be useful in guiding alloying strategies or composition design of Ni-based superalloys.