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Assessment of the feasibility of determining the volume fraction and characteristics of the size, shape and distribution of γ’ phase precipitates in nickel-based superalloys

Szczotok Agnieszka

Technical Transactions

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2023

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Vol. 120, iss. 1

art. no. e2023011

EN

This overview presents a comprehensive exploration of the research methodsemployed for the precise assessment of volume fraction and the detailedcharacterisation of the size, shape and distribution of γ' phase precipitates withinNi-based superalloys. These advanced materials exhibit exceptional mechanicalproperties due to the presence of γ' precipitates. The accurate quantification ofprecipitate parameters is crucial for understanding material behaviour and forthe optimisation of alloy design. In this overview, a spectrum of techniques,including microscopy (SEM, TEM), diffraction (XRD), spectroscopy (EDS, EELS)and advanced imaging (3D-APT, STEM-HAADF, FIB-SEM) is discussed. Strengths,limitations and potential synergies among these methods are highlighted, offeringresearchers a comprehensive toolbox to advance their investigations of γ' phaseprecipitates in Ni-based superalloys.

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Heat transfer by natural convection from a heated square inner cylinder to its elliptical outer enclosure utilizing nanofluids

Bouras Abdelkrim, Taloub Djedid, Driss Zied, Debka Siham

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 2

22--34

EN

In this paper a numerical study of natural convection of stationary laminar heat transfers in a horizontal ring between a heated square inner cylinder and a cold elliptical outer cylinder is presented. A Cu-water nanofluid flows through this annular space. Different values of the Rayleigh number and volume fraction of nanoparticles are studied. The system of equations governing the problem was solved numerically by the fluent calculation code based on the finite volume method and on the Boussinesq approximation. The interior and exterior surfaces are kept at constant temperature. The study is carried out for Rayleigh numbers ranging from 310 to 510. We have studied the effects of different Rayleigh numbers and volume fraction of nanoparticles on natural convection. The results are presented as isotherms, isocurrents, and local and mean Nusselt numbers. The aim of this study is to study the influence of the thermal Rayleigh number and volume fraction of nanoparticles on the heat transfer rate.

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Enhancement of heat transfer in helical coil heat exchangers using nano-fluids

Parveez Malik, Hanief Mohammad

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

279--283

EN

Investigation for heat transfer behaviour of Al2O3 and CuO nano-fluid in helical coil heat exchangers was carried out in this study. The thermo-physical properties of the fluids have temperature dependent nature. The main emphasis was to depict the influence of nano-particle concentration by volume on the characteristics of temperature, rate of heat transfer and heat transfer coefficients (convective). In order to enhance efficiency, density and thermal conductivity are considered to be the most important variables. In comparison to water and for equal flow rate, the rate of heat transfer of nano-fluid increases conspicuously. Efficiency of the helical coil heat exchanger increased by 38.80%.