Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Dynamic Shear Deformation of a Precipitation Hardened Al0.7CoCrFeNi Eutectic High-Entropy Alloy Using Hat-Shaped Specimen Geometry

Version 1 : Received: 9 March 2020 / Approved: 10 March 2020 / Online: 10 March 2020 (03:09:01 CET)

A peer-reviewed article of this Preprint also exists.

Gwalani, B.; Wang, T.; Jagetia, A.; Gangireddy, S.; Muskeri, S.; Mukherjee, S.; Lloyd, J.T.; Banerjee, R.; Mishra, R.S. Dynamic Shear Deformation of a Precipitation Hardened Al0.7CoCrFeNi Eutectic High-Entropy Alloy Using Hat-Shaped Specimen Geometry. Entropy 2020, 22, 431. Gwalani, B.; Wang, T.; Jagetia, A.; Gangireddy, S.; Muskeri, S.; Mukherjee, S.; Lloyd, J.T.; Banerjee, R.; Mishra, R.S. Dynamic Shear Deformation of a Precipitation Hardened Al0.7CoCrFeNi Eutectic High-Entropy Alloy Using Hat-Shaped Specimen Geometry. Entropy 2020, 22, 431.

Abstract

Lamellar eutectic structure of Al0.7CoCrFeNi high-entropy alloy (HEA) is emerging as a promising candidate for structural applications because of its high strength-ductility combination. The alloy consists of a fine-scale lamellar fcc+B2 microstructure with high flow stresses >1500 MPa under quasi-static conditions. The response to shear loading was not investigated so far. This is the first report on the shear deformation of an eutectic structured HEA and effect of precipitation on shear deformation. The dynamic shear response (DSR) of the eutectic HEA was examined in two microstructural conditions, with and without the presence of L12 precipitates. A split-Hopkinson pressure bar (SHPB) was used to compress the hat-shaped specimens to study the local DSR of the alloy. The adiabatic shear bands (ASBs) in two different microstructural conditions were characterized after deformation at dynamic strain rates. The adiabatic shear localization occurs at low strains for the high strength material, and the eutectic microstructure does not delay cracking. The width of ASBs and the extent of plastic deformation around them has been correlated with the rate of straining. Dynamic recrystallization within ASBs and profuse twinning around it was observed. Local mechanical response of individual lamellae before and after shear deformation was examined using nano-indentation.

Keywords

eutectic high-entropy alloy; dynamic shear deformation; split-Hopkinson pressure bar test; hat-shaped specimen; nano-indentation

Subject

Chemistry and Materials Science, Materials Science and Technology

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