Solidification behavior, wettability, steam oxidation resistance and strength of the intermetallic γ′-strengthened cast IN713C Ni-based superalloy

This study investigated the microstructure, tensile strength, wettability, and steam oxidation resistance of as-cast IN713C fabricated by vacuum lost-wax casting. A comprehensive array of techniques, including thermodynamic simulations, synchrotron X-ray diffraction, differential thermal analysis, optical and electron microscopy, tensile testing, sessile drop testing, and a high-temperature oxidation experiment, was employed to characterize the as-cast microstructure. Microstructural analysis revealed a dual-phase dendritic regions, consisting of a γ matrix strengthened by cubic-like secondary γ′ precipitates. The volume fraction of the γ′ phase was 47.5 (±0.5%). Within the dendrites, γ′ precipitates had a mean size of 0.515 μm, whereas in the interdendritic spaces, the average precipitate size increased to 0.635 μm. Carbides of the (Nb, Ti, Mo, Zr)C type contributed approximately 1.7% (±0.5%) to the overall structure. Both thermodynamic modeling and experimental observations indicated that the limited solubility of boron and zirconium in the final stages of solidification led to the formation of minor Ni 7 Zr 2 and (Cr, Mo) 3 B 2 phases. The alloy is characterized by an ultimate tensile strength of 941 MPa (±15 MPa), a yield strength of 714 MPa (±4 MPa), and an elongation of 3.65% (±0.85%). Steam oxidation tests further confirmed the material's durability, displaying a mass gain of just 0.124 mg/cm 2 after 1000 h at 760 °C. Collectively, these results underscore the capability of as-cast IN713C to deliver stable microstructures, superior mechanical strength, and excellent resistance to harsh environmental conditions.