In the current investigation, the effect of Cr on the solidification characteristics and as-cast microstructure of pseudobinary c-d eutectic alloys based on a near-eutectic composition (Ni-5.5Al-13.5Nb at. pct) was investigated. It was found that Cr additions promote the formation of a higher volume fraction of c-d eutectic microstructure in the interdendritic region. Increasing levels of Cr also triggered morphological changes in the c-d eutectic and the formation of c-c¢-d ternary eutectic during the last stage of solidification. A detailed characterization of the as-cast alloys also revealed that Cr additions suppressed the liquidus, solidus, and c¢ precipitation temperature of these c/c¢-d eutectic alloys. A comparison of the experimental results with thermodynamic calculations using the CompuTherm Pandat database (CompuTherm LLC, Madison, WI) showed qualitative agreement.

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