Microstructure evolution and mechanical properties of CrFeNixV0.64Ta0.36 eutectic high-entropy alloys.

Eutectic high entropy alloys (EHEAs) have attracted considerable interest because of their excellent casting fluidity and outstanding mechanical properties. In this study, a novel system of EHEAs, namely CrFeNi x V 0.64 Ta 0.36 (1.3 ≤ x ≤ 1.9) was designed and prepared. The microstructure evolution and mechanical properties of CrFeNi x V 0.64 Ta 0.36 EHEAs were investigated in as-cast state. The results showed that the alloy was composed of σ-phase, Fe 7 Ta 3 -type intermetallic compounds (IMC), and a small amount of the eutectic phase when x = 1.3. A rare bimodal eutectic microstructure [face-centered-cubic (FCC) structure /σ + Fe 7 Ta 3 -type IMC] was observed in EHEAs, even in high entropy alloys when x = 1.6, 1.7, 1.8, and 1.84. The typical hypo-eutectic microstructure was acquired when x was increased to 1.9. The fully eutectic composition, i.e., CrFeNi 1.85 V 0.64 Ta 0.36 with alternatingly lamellar FCC and Fe 7 Ta 3 -type IMC structures exhibited the best mechanical properties, with the compressive yield strength, fracture strength, and engineering strain being 1475.9 MPa, 2799 MPa, and 38.095%, respectively. [Display omitted] • A rare bimodal eutectic microstructure was observed in EHEAs, even in HEAs and conventional alloys. • The fully eutectic Ni1.85 gained best mechanical properties with σ s and ε being 1475.3 MPa and 38.095%, respectively. [ABSTRACT FROM AUTHOR]