Investigations of quaternary interdiffusion in a constituent system of high entropy alloys

Kaustubh Kulkarni,Gyanendra Pratap Singh Chauhan

doi:10.1063/1.4931806

Kaustubh Kulkarni, Gyanendra Pratap Singh Chauhan

Open Access

https://doi.org/10.1063/1.4931806

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Journal: AIP Advances	Publication Date: Sep 1, 2015
Citations: 69	License type: CC BY 3.0

Affiliation: Indian Institute of Technology Kanpur

Abstract

Interdiffusion was investigated at 1000°C in a quaternary Fe-Ni-Co-Cr system, which is an essential constituent of many high-entropy alloys. The relative values of main and cross interdiffusion coefficients determined from concentrations and interdiffusion fluxes developed in a single diffusion couple indicate that significant diffusional interactions exist in this system. Thermodynamic interactions between the binary constituents were analyzed based on the activity coefficient relations and it is shown that the observed diffusional interactions of a component with others are consistent with relative thermodynamic interactions between them.

Highlights

Multicomponent alloys containing equimolar or near-equimolar mixture of five or more elements have been a topic of great research over past decade or so.[1,2,3,4,5,6,7] As against the expectation of developing complicated microstructure due to the presence of multiple elements, these alloys are seen to exist as a single phase solid solution or a mixture of two or three simple solid solutions
Interdiffusion was investigated at 1000◦C in a quaternary Fe-Ni-Co-Cr system, which is an essential constituent of many high-entropy alloys
Thermodynamic interactions between the binary constituents were analyzed based on the activity coefficient relations and it is shown that the observed diffusional interactions of a component with others are consistent with relative thermodynamic interactions between them

Summary

Introduction

Multicomponent alloys containing equimolar or near-equimolar mixture of five or more elements have been a topic of great research over past decade or so.[1,2,3,4,5,6,7] As against the expectation of developing complicated microstructure due to the presence of multiple elements, these alloys are seen to exist as a single phase solid solution or a mixture of two or three simple solid solutions. In addition to having high elevated temperature strength, these alloys are reported to have sluggish diffusion kinetics based on the slow rates of precipitation and coarsening observed in them.[8,9] there has been no study found in literature on estimating diffusion coefficients in these concentrated multicomponent alloys except the one reported by Tsai et al.[10] In multicomponent alloys, diffusional interactions or the cross effects of various diffusing species play an important role in guiding the diffusion kinetics. These diffusional interactions may be manifested in terms of regions of uphill diffusion and zero flux planes, and can enhance or reduce the diffusion of an element.[11,12] understanding diffusional interactions in HEA’s is essential in order to explain the sluggish kinetics observed in these alloys

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Conclusion