Tensile properties of an AlCrCuNiFeCo high-entropy alloy in as-cast and wrought conditions

Extensive multistep forging at 950 degrees C was applied to the cast AlCuCrFeNiCo high-entropy alloy to transform the cast coarse dendritic structure into a fine equiaxed duplex structure consisting of the mixture of BCC and FCC phases, with the average grain/particle size of similar to 1.5 +/- 0.9 mu m. Tensile properties of the alloy in the as-cast and forged conditions were determined in the temperature range of 20-1000 degrees C. The hot forged alloy was stronger and more ductile during testing at room temperature, than the as-cast alloy. The yield stress (YS), ultimate tensile strength (UTS), and tensile ductility (delta) of the forged condition were 1040 MPa, 1170 MPa, and 1%, respectively, against 790 MPa, 790 MPa and 0.2% for the as-cast condition. In both conditions, the alloy showed brittle to ductile transition (BDT), with a noticeable increase in the tensile ductility within a narrow temperature range. In the as-cast condition, this transition occurred between 700 and 800 degrees C, while in the forged condition, it was observed between 600 and 700 degrees C. With an increase in the testing temperature above the BDT, a continuous decrease in tensile flow stress and an increase in tensile ductility were observed. In the temperature range of 800-1000 degrees C, the forged alloy showed superplastic behavior. The tensile elongation was above 400% and reached 860% at 1000 degrees C. (C) 2011 Elsevier B.V. All rights reserved.