The ultrahigh charpy impact toughness of forged AlxCoCrFeNi high entropy alloys at room and cryogenic temperatures

• The tensile strength and ductility increase with the decrease of the temperature.
• The tensile strength and elongation of Al0.1CoCrFeNi alloy reach of 1042 MPa and 81.6% at 77 K, respectively.
• The Charpy impact energy of Al0.1CoCrFeNi alloy can reach to 420 J at room temperature.

AlxCoCrFeNi high-entropy alloys (HEAs) with different aluminum contents (i.e., x values in molar ratio, where x = 0.1, 0.3) were initially prepared using vacuum magnetic levitation melting and, then, plate samples were prepared by hot forging method. The two five-element HEAs, Al0.1CoCrFeNi and Al0.3CoCrFeNi, both had a simple face-centered cubic (FCC) structure. The measurements of Charpy impact energy with V-type notch and tensile tests were carried out at different temperatures. It was observed that the tensile strength and elongation increased with decreasing temperatures and reached 1042 MPa and 81.6% at 77 K, respectively, for the Al0.1CoCrFeNi alloy. The Charpy impact energy reached a maximum value of 420 J at room temperature for the Al0.1CoCrFeNi alloy.

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