Thermodynamic Evaluation of the Phase Stability and Microstructural Characterization of a Cast B1914 Superalloy

• Published in: Journal of materials engineering and performance 2014-03, Vol.23 (3), p.819-825
• Main Authors: da Silva Costa, Alex Matos, Nunes, Carlos Angelo, Baldan, Renato, Coelho, Gilberto Carvalho
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Corrosion and Coatings; Cross-disciplinary physics: materials science; rheology; Engineering Design; Exact sciences and technology; Materials Science; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Quality Control; Reliability; Safety and Risk; Solidification; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-013-0814-6

The boron-carbon superalloys (BC alloys) were developed to reduce the carbon content of the alloys to less than 0.02 wt.% and increase the boron content to 0.1 wt.% in some Ni-based superalloys. In this study, we have used characterization techniques, such as DTA, XRD, SEM coupling, and thermodynamic calculation using Thermo-Calc software, to obtain information about the phase transformation reaction temperatures and the elemental compositions of the microstructural constituents encountered in the B1914 superalloy. The microstructure of the B1914 superalloy was composed of a gamma (γ) phase with a dendritic structure and gamma prime (γ′) phase with a cuboidal shape. Precipitates of γ′ and a lamellar eutectic, composed of γ/(Mo,Cr,Ni) 3 B 2 , were identified in the interdendritic region. The thermodynamic calculation results have shown to be a valuable tool for predicting the transformation temperature, such as liquidus, γ’ solvus, and incipient melting point. These transformations are important parameters used in casting simulation software for determining the heat treatment and welding repair conditions for parts made from this alloy.