Data-Driven Design of High-Purity Ni–Cr–Nb Master Alloy and Its Application in Scale-Up GH4169D Alloy

ABSTRACT: To address the challenge of further reducing impurities in raw materials for high-purity melting of industrial-superalloys such as GH4169D, this study employed a CALPHAD-based high-throughput computational approach to establish the composition-phase stability-impurity behavior relationship. A low-melting-point, high-cleanliness Ni–Cr–Nb master alloy was developed and characterized with oxygen and nitrogen contents of 76 ppm and 36 ppm, respectively, and an inclusion number density of approximately 540 ± 20 cm⁻² and an average inclusion size of 2.2 ± 0.15 μm, demonstrating excellent cleanliness and compositional controllability. In industrial-scale 3-ton GH4169D melting trials using the Ni–Cr–Nb master alloy, the oxygen content was reduced from 12 ppm to 8 ppm. The inclusion number densities at the ingot center, R/2 position, and edge were decreased by 7.75%, 36.1%, and 81.5%, respectively, while the maximum inclusion size was reduced from approximately 28 μm to 9–17 μm. The results indicate that the developed master alloy effectively suppresses the formation, growth, and radial segregation of inclusions in GH4169D, significantly enhancing its metallurgical uniformity and cleanliness. Furthermore, melting efficiency increased by 52.6%, and production costs decreased by approximately 2.3% per ton, highlighting substantial process and economic advantages. This work establishes a closed-loop research framework integrating “CALPHAD-based experimental design—industrial pilot-scale validation—production-line metallurgical quality evaluation”. It confirms the effectiveness of the master alloy strategy for high-purity scale-up superalloy production and provides a transferable technological pathway for the compositional design and industrial application of other master alloy systems and commercial alloys.