Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/113893
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Type: Journal article
Title: Medium entropy alloy CoCrNi coatings: Enhancing hardness and damage-tolerance through a nanotwinned structuring
Author: Cao, F.
Munroe, P.
Zhou, Z.
Xie, Z.
Citation: Surface and Coatings Technology, 2018; 335:257-264
Publisher: Elsevier BV
Issue Date: 2018
ISSN: 0257-8972
1879-3347
Statement of
Responsibility: 
Fuyang Cao, Paul Munroe, Zhifeng Zhou, Zonghan Xie
Abstract: Medium entropy alloys (MEA) are defined as alloys consisting of three equiatomic elements, such as CoCrNi. MEAs are reported to have superior mechanical properties and high thermodynamic stability, as well as excellent fracture toughness at cryogenic temperatures. Here, we investigate a series of equiatomic medium entropy alloy coatings, containing three elements, Co, Cr, Ni. These coatings were deposited onto M2 steel substrates with a range of coating thicknesses using a DC magnetron sputtering system using a CoCrNi alloy target (1:1:1 at.%). The microstructure and mechanical properties were examined by a number of characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and nanoindentation. XRD analysis showed that the coatings were dominated by a fcc CoCrNi phase, with a smaller amount of hcp Co. TEM analysis demonstrated that the elongated grains contained a high density of {111} nanotwins. In addition, the residual stresses in the coatings were analysed using X-ray diffraction by adopting the conventional sin2ψ method. A high hardness value, ~ 10 GPa, was determined by nanoindentation of these coatings. Exceptional damage-tolerance was also found in these coatings under contact loading. It is believed that the nanotwinned structure is responsible for the high hardness and damage tolerance observed in the new coatings.
Keywords: Medium entropy alloys; CoCrNi; nanotwinned structure; hardness; damage tolerance
Description: Available online 10 December 2017
Rights: © 2017 Elsevier B.V. All rights reserved.
DOI: 10.1016/j.surfcoat.2017.12.021
Grant ID: http://purl.org/au-research/grants/arc/DP150102417
Published version: http://dx.doi.org/10.1016/j.surfcoat.2017.12.021
Appears in Collections:Aurora harvest 3
Mechanical Engineering publications

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