Evolution of Texture, Strain, and Grain Boundary Constitution in Copper�Chromium Coatings and its Effect on Coating Corrosion Behavior

Lala, SRF and Gupta, A and Srivastava, C (2021) Evolution of Texture, Strain, and Grain Boundary Constitution in Copper�Chromium Coatings and its Effect on Coating Corrosion Behavior. In: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science .

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Abstract

Microstructural alterations in electrodeposited Cu�Cr coatings (1.5, 3.6, and 6.5 wt pct Cr) and their impact on the coating corrosion behavior have been investigated. The coatings obtained were compact and crack free. Compositional analysis of the coating cross section revealed the presence of Cr both within the grains and in the grain boundary regions. Analysis of the X-ray diffraction pattern revealed a decrease in the grain size and increase in the coating strain with increase in the Cr content. Potentiodynamic polarization and electrochemical impedance spectroscopy revealed that the corrosion resistance increased for initial additions of Cr (1.5 and 3.6 wt pct) and then it decreased for higher Cr content (6.5 wt pct). The corrosion current density (icorr) values obtained for pure copper, CuCr (1.5 wt pct), CuCr (3.6 wt pct), and CuCr (6.5 wt pct) coatings were 13.4, 11.2, 9.6, and 13.8 µA/cm2, respectively. The corresponding polarization resistance values (Rp) obtained were 1535.36, 1643.82, 1955.55, and 1512.28 Ω cm2, respectively. Electron-backscattered diffraction technique was used to correlate the electrochemical properties of the coatings with growth texture and grain boundary constitution. It was found that with the addition of Cr, there was a significant increase in the fraction of low-energy low-angle grain boundaries (LAGBs) which increased the corrosion resistance of the Cu-3.6wt pct Cr coating. The fractions of LAGBs for pure Cu and CuCr (3.6 wt pct) were 28 and 42 pct, respectively. Poor corrosion resistance in case of CuCr-3 coating containing maximum Cr content was due to the presence of high coating strain. © 2021, The Minerals, Metals & Materials Society and ASM International.

Item Type:	Journal Article
Publication:	Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Publisher:	Springer
Additional Information:	The copyright for this article belongs to Springer
Keywords:	Chromium; Chromium alloys; Copper alloys; Copper corrosion; Corrosion resistance; Corrosion resistant coatings; Corrosive effects; Electrochemical corrosion; Electrochemical impedance spectroscopy; Grain boundaries; Intergranular corrosion; Polarization; Textures, Chromium coatings; Copper chromium; Corrosion behaviour; Cr coatings; Cr content; Crack free; Grain-boundaries; Low angle grain boundaries; Microstructural alterations; Texture boundary, Binary alloys
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	13 Dec 2021 11:38
Last Modified:	13 Dec 2021 11:38
URI:	http://eprints.iisc.ac.in/id/eprint/70760

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