The phase composition characteristics of AlCoCrFeNi high entropy alloy heat-treated by simple normalizing treatment and its effects on mechanical properties

The AlCoCrFeNi high entropy alloy (HEA) has been regarded as a potential candidate for refractory material due to its uniqueness, and its brittleness can be tuned by heat treatment. In this work, we propose a new heat treatment process to tailor the phases of AlCoCrFeNi HEA, and reach the optimum trade-off of strength and ductility. The results show that normalizing treatment in air can be used to instead of quenching in water to obtain the same phase composition and even better performance of AlCoCrFeNi HEA, then avoiding the shortcomings of quenching, reducing production costs, improving production efficiency and expanding its application prospects. The detailed phase compositions and required temperature of normalizing treatment are B2 + BCC (as-cast) → B2 + BCC + little FCC + little σ (700 °C) → B2 + BCC + FCC + σ (900 °C) → B2 + BCC + little FCC (1100 °C) → B2 + BCC (1300 °C). The 1100 °C treated alloy has the highest ultimate compressive strength (3429 MPa) and compression ratio (33.6 %), and reaches the best strength-ductility trade-off due to its special phase composition and microstructure. [Display omitted] •Normalizing treatment can be used to instead of quenching in AlCoCrFeNi HEA.•The 1100 °C treated alloy has the highest σUCS of 3429 MPa and εP of 33.6 %.•The 1100 °C treated alloy reaches the best strength-ductility trade-off.