Microstructure and mechanical properties variation with Ni content in Al_0.8CoCr_0.6Fe_0.7Ni_x (x = 1.1, 1.5, 1.8, 2.0) eutectic high-entropy alloy system

Abstract

Eutectic high-entropy alloys have drawn extensive attention because of their remarkable performance on the combination of strength and plasticity. In this study, a new Al 0.8 CoCr 0.6 Fe 0.7 Ni x (x=1.1, 1.5, 1.8, 2.0) eutectic high-entropy alloy system was designed; the microstructure and mechanical properties variation of alloys with the change in Ni content were investigated detailly. All of four alloys exhibited FCC+B2 dual-phase structure, while the volume fraction of FCC phase increased from 44% to 90% with an increase in Ni content. Meanwhile, the microstructure of alloys variated from an irregular dendrite morphology to a lamellar eutectic microstructure, and finally to a hypoeutectic microstructure composed by primary FCC phase and the rest eutectic mixture. Accordingly, the yield strength of alloys decreased from 625 MPa to 415 MPa, and the total elongation increased from 7.4% to 21.8%. The Al 0.8 CoCr 0.6 Fe 0.7 Ni 1.5 alloy displayed a nano-scale lamellar eutectic microstructure and exhibited a relatively good combination of strength and plasticity in these four alloys, with a yield strength of 490 MPa, a ultimate strength of 980 MPa and a total elongation of 14.8%. The findings could contribute to explore HEAs with good combination of strength and plasticity and promote the applications of high-entropy alloys in industrial fields.

Hierarchical crack buffering triples ductility in eutectic herringbone high-entropy alloys

“…Its elongation is comparable to that of widely studied, high-ductility, fully homogenized face-centered cubic high-entropy alloys (HEAs) (24)(25)(26)(27). The resulting strength-ductility combination, and especially the uniform ductility, in the directionally solidified EHEA outperforms that of any other as-cast eutectic and neareutectic HEAs (14,15,19,20,22,23,(28)(29)(30)(31)(32)(33) (Fig. 2B).…”

“…Inset shows the corresponding strain-hardening curves.MDIH and MBIH refer to multi-slip dislocation-induced hardening and microbandinduced hardening, respectively; e U , uniform strain; s y , yield strength; s UTS , ultimate tensile strength. (B) Yield strength versus uniform strain of the directionally solidified EHEAs compared with those of previously reported as-cast eutectic and near-eutectic HEAs(14,15,19,20,22,23,(28)(29)(30)(31)(32)(33). (N-)EHEAs refers to eutectic and near-eutectic HEAs.…”

Nanostructured High Entropy Alloys as Structural and Functional Materials

“…Ultimate tensile strength versus elongation to fracture at room temperature of the nanostructure-strengthened HEAs and the nanostructure-free HEAs. − The data points of the nanostructure-strengthened HEAs include that of nanoprecipitation-strengthened, ,,,,,− ,,,− eutectic, ,− spinodal, ,− and nanograin-strengthened HEAs. , …”

Development of high entropy alloys (HEAs): Current trends

“…Furthermore, Fe–Nb is abundant in the lave phase. The effect of the laves phase is more thermally stable than other phases [ 68 ].…”