Simultaneous enhancement of strength and ductility in an AlCoCrFeNi2.1 eutectic high-entropy alloy via friction stir processing

Lamellar eutectic structure of as-cast AlCoCrFeNi2.1 was tailored by friction stir processing (FSP). During FSP, lamellar B2 phase was broken into ultrafine-grained particles, with dissolution of Cr-rich precipitates in B2 and formation of Al-rich precipitates in FCC (L1(2)). Dynamic recrystallization of FCC/L1(2) and B2 reduced grain size to less than similar to 0.5 mu m. The combined effect of microstructural evolution in the processed region improved the ultimate tensile strength from similar to 1000 MPa to 1360 MPa, the ductility from similar to 6.5% to 10%, and the microhardness from similar to 300 HV0.2 to 450 HV0.2. (C) 2018 Elsevier B.V. All rights reserved.