Dynamic Shear Deformation of a Precipitation Hardened Al

Lamellar eutectic structure in Al0.7CoCrFeNi high-entropy alloy (HEA) is emerging as apromising 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 &gt
1300 MPaunder quasi-static tensile deformation and &gt
10% ductility. The response to shear loading was notinvestigated so far. This is the first report on the shear deformation of a eutectic structured HEA andeffect of precipitation on shear deformation. A split-Hopkinson pressure bar (SHPB) was used tocompress the hat-shaped specimens to study the local dynamic shear response of the alloy. Thechange in the width of shear bands with respect to precipitation and deformation rates was studied.The precipitation of L12 phase did not delay the formation of adiabatic shear bands (ASB) or affectthe ASB width significantly, however, the deformed region around ASB, consisting of high densityof twins in fcc phase, was reduced from 80 &mu
m to 20 &mu
m in the stronger precipitation strengthenedcondition. We observe dynamic recrystallization of grains within ASBs and local mechanicalresponse of individual eutectic lamellae before and after shear deformation and within the shearbands was examined using nano-indentation.