Effects of minor Nb alloying on the thermal stability and mechanical responses of a γ/γ′ type high-entropy alloy with high Fe content

He, J and Li, N and Makineni, SK and Zhao, Y and Liu, W and Wang, L and Wang, Z and Song, M (2022) Effects of minor Nb alloying on the thermal stability and mechanical responses of a γ/γ′ type high-entropy alloy with high Fe content. In: Materials Science and Engineering A, 851 .

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Abstract

In this work, by equipping the high-entropy concept we designed a γ/γ′-type high-entropy alloy with high Fe content (25 at.%), and further alloyed Nb to evaluate its microstructural stability and mechanical responses. We found that after 850 °C annealing, 1.5 at.% Nb addition can completely suppress the discontinuous precipitation (DP) reaction. The high γ/γ′ structural stability even after one month ageing at 800 °C is believed to be originated from strong partitioning of Nb to γ′. The onset of continuous inter-mass-flow of Fe and Nb across the γ/γ′ interface further enhances the γ′ ripening resistance. The increased tensile strength in the Nb-alloyed HEA across a wide temperature range (23–900 °C) is because of the increased volume fraction and anti-phase boundary energy of γ′. The corresponding lowered ductility is then attributed to the absence of the DP colony that not only acts as a stress buffer zone but also introduces grain boundary serration to withstand intergranular cracking.

Item Type:	Journal Article
Publication:	Materials Science and Engineering A
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to the Elsevier Ltd.
Keywords:	Grain boundaries; High-entropy alloys; Iron; Niobium alloys; Precipitation (chemical); Stability; Tensile strength; Textures, Atom-probe tomography; Discontinuous precipitation; Entropy concept; Fe content; GB embrittlement; High entropy alloys; High temperature tension; High-Fe; Highest temperature; Mechanical response, Entropy
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	30 Aug 2022 05:27
Last Modified:	30 Aug 2022 05:27
URI:	https://eprints.iisc.ac.in/id/eprint/76267

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