Thermophysical modeling of niobium alloys informs materials selection and design for high-temperature applications

• Published in: Materials & design Vol. 248; p. 113456
• Main Authors: Bowling, L.S., Wang, A.T., Philips, N.R., Riffe, W.T., Matejczyk, D.E., Skelton, J.M., Hopkins, P.E., Fitz-Gerald, J.M., Agnew, S.R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2024; Elsevier
• Subjects: Elastic modulus; Performance index; Refractory; Specific heat capacity; Thermal conductivity; Thermal expansion; Refractory; Elastic modulus; Thermal expansion; Thermal conductivity; Specific heat capacity; Performance index
• ISSN: 0264-1275
• DOI: 10.1016/j.matdes.2024.113456

[Display omitted] •Room temperature moduli of most Nb-alloys agree well with mole fraction weighted rule-of-mixture calculations.•A single, linear temperature dependence of the elastic properties is suggested for all Nb-alloys considered in this study.•A single Smith-Palmer equation adequately describes the thermal conductivity most of the Nb-based alloys investigated.•Thermal conductivity of WC-3009 is significantly lower than the thermal conductivity than the other Nb-alloys investigated.•A performance index is introduced for lightweight, panel-shaped applications subject to thermal gradients or transients. There is renewed interest in refractory alloys that possess higher service temperatures than incumbent Ni-based superalloys (⪆1100 °C). Thermophysical property data for six Nb-alloys are gathered from the literature and reviewed, and new data are provided for two Hf-containing Nb-alloys; elastic modulus, thermal expansion, thermal conductivity, and heat capacity are presented for C103, and new thermal conductivity data are provided for a higher strength alloy, WC-3009. Comparisons with Ni-superalloys and other refractory-metal based alloys provide context. Physics-based models are provided that describe the temperature dependencies of the Young’s modulus, coefficient of thermal expansion and density, and thermal conductivity; such that fair comparisons can be made across alloys for any given condition. The results suggest a need for improved understanding of the temperature dependence of the elastic modulus. A performance index is introduced for making informed materials selection decisions in the context of lightweight, panel-shaped applications subjected to sharp thermal transients or steep thermal gradients, and the significant strain rate sensitivity of Nb-alloys is highlighted. Ultimately, the relative value of current commercial alloy, C103, as well as the promise of specific Nb-W-Zr alloys are highlighted.