Effect of Al additions on the microstructures and tensile properties of AlₓCoCr₃Fe₅Ni high entropy alloys

Abstract

AlₓCoCr₃Fe₅Ni high entropy alloys with varying aluminum contents (x = 0, 0.1, 0.2 and 0.3) were synthesized by induction melting and casting method. The microstructures and tensile properties of the new HEAs were investigated. Different regions of CoCr₃Fe₅Ni matrix HEA have different microstructures. With the increase of Al content, the microstructure changes from dendrite to lamellar eutectic and dual-phase structure comprising FCC and BCC phases was found in all four samples with different ratios. The volume fraction of BCC phase increased. The ultimate tensile strength (UTS) of the alloy increased, with the highest UTS (1018.9 MPa) achieved at x = 0.3 in this work. On the other hand, increasing Al content further induced distortion of the crystalline lattice and enhanced the alloy strength.