Solving the issues of multicomponent diffusion in an equiatomic NiCoFeCr medium entropy alloy

Dash, A and Esakkiraja, N and Paul, A (2020) Solving the issues of multicomponent diffusion in an equiatomic NiCoFeCr medium entropy alloy. In: Acta Materialia, 193 . pp. 163-171.

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Abstract

Estimating the diffusion coefficients experimentally in a four-component inhomogeneous alloy following the conventional diffusion couple method by intersecting three couples at the same composition is difficult unless a small composition range of constant diffusivity is identified. Additionally, the intrinsic diffusion coefficients of the components cannot be estimated in a system with more than two components. To solve these issues, we have followed the pseudo-binary and pseudo-ternary diffusion couple methods for estimating the diffusion coefficients at the equiatomic composition of NiCoFeCr medium entropy alloy. Along with the pseudo-binary interdiffusion coefficients, we have estimated the intrinsic diffusion coefficients of all the components by designing the pseudo-binary couples such that Ni and Co develop the diffusion profiles keeping Fe and Cr constant in one couple and Fe and Cr develop the diffusion profiles keeping Ni and Co constant in another couple. Subsequently, we have proposed the relations for calculating the tracer diffusion coefficients utilizing the thermodynamic details. We have found a good match with the data estimated directly following the radiotracer method at the equiatomic composition. Following, we have produced three pseudo-ternary diffusion couples intersecting at the compositions close to the equiatomic composition. The main pseudo-ternary interdiffusion coefficients of Fe are found to be higher than Ni and Co. Therefore, we have estimated different types of diffusion coefficients highlighting the complex diffusion process in the four-component NiCoFeCr medium entropy alloy. © 2020 Acta Materialia Inc.

Item Type:	Journal Article
Publication:	Acta Materialia
Publisher:	Acta Materialia Inc
Additional Information:	The copyright of this article belongs to Acta Materialia Inc
Keywords:	Chromium; Chromium alloys; Cobalt; Cobalt alloys; Entropy; Iron; Iron alloys; Nickel, Complex diffusions; Composition ranges; Diffusion profiles; Equiatomic composition; Inter-diffusion coefficients; Multi-component diffusion; Radiotracer method; Tracer diffusion coefficients, Diffusion
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	12 Aug 2020 11:39
Last Modified:	12 Aug 2020 11:39
URI:	http://eprints.iisc.ac.in/id/eprint/65478

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