Thermal transport properties of Ni–Co-based superalloy

Asuka Miura,Kyoko Kawagishi,Ken-Ichi Uchida,Toshio Osada

doi:10.1063/5.0030847

Abstract

We report systematic measurements of thermal transport properties of a Ni–Co-based superalloy at temperatures ranging from room temperature to around 800 K. In this temperature range, the thermal diffusivity and conductivity of the superalloy monotonically increase with an increase in the temperature, while the specific heat capacity is almost temperature-independent. We found that the observed thermal conductivity of the Ni–Co-based superalloy is higher than the electronic thermal conductivity expected from the Wiedemann–Franz law, indicating the substantial contribution of phonon thermal conductivity. The temperature dependence of the phonon thermal conductivity for the Ni–Co-based superalloy was observed to be weaker than that for other Ni-based alloys, which can be qualitatively explained by enhanced phonon scattering due to small γ′-phase precipitates in the superalloy. This result suggests possible tuning of the thermal conductivity of the superalloy based on phonon transport engineering.

Highlights

Bal. 11.70 27.0 3.40 1.90 4.40 3.20 2.20 0.35 0.50 Spherical 0.550 ± 0.012 0.550 ± 0.012 which are grain boundary strengthening elements.6 Nominal compositions of the binary and quaternary alloys were designed so that the volume fraction fV of the γ′ phase is similar to that of the TMP-5002 superalloy prepared at 1143 K
The γ′ precipitate morphologies in the aged alloys were observed by field emission-scanning electron microscopy (ZEISS, Gemini SEM 300)
The area fraction f A and size distribution of the γ′ precipitates were analyzed from the scanning electron microscopy (SEM) images by using Image J software

Summary

Introduction

Bal. 11.70 27.0 3.40 1.90 4.40 3.20 2.20 0.35 0.50 Spherical 0.550 ± 0.012 0.550 ± 0.012 which are grain boundary strengthening elements.6 Nominal compositions of the binary and quaternary alloys were designed so that the volume fraction fV of the γ′ phase is similar to that of the TMP-5002 superalloy prepared at 1143 K. We measured the thermal conductivity of a Ni–Co-based superalloy called TMP-5002 in the temperature range from room temperature to 800 K and compared the results with the thermal conductivity of other Ni-based alloys, where the TMP-5002 superalloy is known to exhibit the best heat-resistant properties and is close to practical applications.6 The relationship between the temperature dependence of the thermal conductivity and the microstructures of the alloys is discussed in terms of phonon thermal transport.

Results

Conclusion