Comparison of Thermodynamic Predictions and Experimental Observations on B Additions in Powder-Processed Ni-Based Superalloys Containing Elevated Concentrations of Nb

Stoichko Antonov*, Jiajie Huo, Qiang Feng, Dieter Isheim, David N. Seidman, Eugene Sun, Sammy Tin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Boron additions to Ni-based superalloys are considered to be beneficial to the creep properties of the alloy, as boron has often been reported to increase grain boundary cohesion, increase ductility, and promote the formation of stable boride phases. Despite the importance, it is not well understood whether these improvements are associated with the presence of elemental boron or stable borides along the grain boundaries. In this investigation, two experimental powder-processed Ni-based superalloys containing elevated levels of Nb were found to exhibit increased solubility for B in the γ matrix when compared to similar commercial Ni-based superalloys. This resulted in an overall lower B concentration at grain boundaries that suppressed boride formation. As the predictive capability of CALPHAD database models for Ni-based superalloys have improved over the years, some discrepancies may still persist around compositionally heterogeneous features such as grain boundaries. Improved quantification of the characteristic partitioning of B as a function of the bulk alloy composition is required for understanding and predicting the stability of borides.

Original languageEnglish (US)
Pages (from-to)729-739
Number of pages11
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume49
Issue number3
DOIs
StatePublished - Mar 1 2018

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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