On Sluggish Diffusion in Fcc Al–Co–Cr–Fe–Ni High-Entropy Alloys: An Experimental and Numerical Study

Qin Li,Qing Chen,Lijun Zhang,Jing Zhong,Weimin Chen,Zi-Kui Liu

doi:10.3390/met8010016

Qin Li, Qing Chen + Show 4 more

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https://doi.org/10.3390/met8010016

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Journal: Metals	Publication Date: Dec 30, 2017
Citations: 61	License type: CC BY 4.0

Affiliation: Central South University, Pennsylvania State University

Abstract

High-throughput measurement using the numerical inverse method combined with the diffusion multiple technique was employed to determine the composition-dependent interdiffusion coefficients in fcc Al–Co–Cr–Fe–Ni high-entropy alloys at 1273, 1323, and 1373 K. The reliability of the obtained interdiffusion coefficients was confirmed by comparing the model-predicted composition/interdiffusion flux profiles with the experimental data. The tracer diffusivities of the components were then predicted based on the obtained interdiffusion coefficients and the simplified thermodynamic description. The diagonal interdiffusion coefficients in the present high-entropy alloys were comprehensively compared with those in conventional fcc alloys. Therefore, the sluggish diffusion effect does not apply for all the elements in the present fcc Al–Co–Cr–Fe–Ni high-entropy alloys. A similar result was also observed for the evaluated tracer diffusivities.

Highlights

The high-entropy alloys (HEAs) (or multi-principle element alloys (MPEAs)) initially proposed byYeh and Huang in 1995 [1] have drawn increasing attention because of their comprehensive beneficial mechanical, magnetic, and electrochemical characteristics
Comparison of the results revealed that, for Co–Cr–Fe–Mn–Ni HEAs, the sluggish diffusion feature was plausible for the interdiffusion coefficients rather than the tracer diffusivities
All the interdiffusion flux points were directly evaluated from the raw experimental concentration points

Summary

Introduction

The high-entropy alloys (HEAs) (or multi-principle element alloys (MPEAs)) initially proposed by. Yeh and Huang in 1995 [1] have drawn increasing attention because of their comprehensive beneficial mechanical, magnetic, and electrochemical characteristics These characteristics render these HEAs suitable for numerous potential uses. The aforementioned outstanding properties are usually directly attributed to the four core effects on HEAs [2,5] Among these effects, sluggish diffusion is identified as the one responsible for many distinct characteristics of HEAs [6], such as the deceleration of grain growth, exceptional thermal stability, and formation of nanostructures. Dabrowa et al [11] measured the tracer diffusivities of the elements, except that for Al, in the Al–Co–Cr–Fe–Ni quinary system and found the occurrence of the sluggish diffusion effect in HEAs

Experimental

Numerical Inverse Method

Results and Discussion

Comparison

Conclusions