Anisotropy of Additively Manufactured Co-28Cr-6Mo Influences Mechanical Properties and Biomedical Performance

Acharya, S and Gopal, V and Gupta, SK and Nilawar, S and Manivasagam, G and Suwas, S and Chatterjee, K (2022) Anisotropy of Additively Manufactured Co-28Cr-6Mo Influences Mechanical Properties and Biomedical Performance. In: ACS Applied Materials and Interfaces, 14 . pp. 21906-21915.

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Abstract

Additive manufacturing (AM) of biomedical alloys such as Co-Cr-Mo alloys holds immense potential for fabricating implants with complex geometry and tailored to meet patient-specific needs. However, layer-by-layer fabrication in AM processes results in undesired anisotropy due to the solidification texture and grain morphology. The present study aimed to investigate the effect of build orientation on the mechanical properties and functional performance, including tribocorrosion behavior and cytocompatibility of an orthopedic Co-28Cr-6Mo alloy manufactured by selective laser melting. Although the fabricated alloy showed weak crystallographic texture due to the rotational scanning strategy, significant anisotropy was found in the tensile properties due to the grain size and morphology. The presence of larger, elongated grains along the build direction as compared to smaller, equiaxed grains perpendicular to the build direction imparted the observed tensile anisotropy. Quantitative analysis based on current models for strengthening mechanisms is insufficient to explain the observed anisotropy, which is ascribed to the possible role of the cellular dendrites and stacking fault strengthening in Co-Cr alloys. Unlike the electrochemical behavior, which was largely independent of the build orientation, the bio-tribocorrosion studies revealed an anisotropic wear rate under fretting conditions. Osteoblast attachment and proliferation were found to be higher on the plane perpendicular to the build direction, owing to the differences in grain size. This work provides novel insights into the role of the manufacturing parameters in a selective-laser-melted Co-Cr alloy and its potential application in engineering load-bearing orthopedic implants.

Item Type:	Journal Article
Publication:	ACS Applied Materials and Interfaces
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to the American Chemical Society
Keywords:	Additives; Anisotropy; Binary alloys; Cobalt alloys; Fabrication; Grain size and shape; Melting; Molybdenum alloys; Morphology; Selective laser melting; Ternary alloys; Textures; Tribology, Build direction; Build orientation; Grain morphologies; Grainsize; Laser powder bed fusion; Laser powders; Orthopaedic biomaterials; Performance; Powder bed; Selective laser melting, Chromium alloys, alloy, anisotropy; chemistry; freezing; human; laser, Alloys; Anisotropy; Freezing; Humans; Lasers
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	05 Jul 2022 11:51
Last Modified:	05 Jul 2022 11:51
URI:	https://eprints.iisc.ac.in/id/eprint/74157

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