Microstructure refinement and enhanced mechanical properties in rapid-quenched MnCrFeCoNi high-entropy alloy

High-entropy alloys (HEAs) have gained significant attentions in recent years, due to their unique properties derived from the combination of multiple elements in equimolar or near-equimolar ratios. The mechanical properties of HEAs are influenced by microstructural characteristics. In this study, MnCrFeCoNi HEA ribbons were produced using a technique called melt spinning, for which the wheel speed was adjusted to control the undercooling levels. The rapid solidification process under undercooling condition resulted in refined grain sizes to micrometers in the ribbons. One notable feature was the appearance of twin boundaries, which especially accounted for approximately 7.36 % of the microstructure for the ribbons produced at a wheel speed of 10 m/s. For the ribbons with thickness of micrometer scale, the mechanical properties (ultimate tensile strength up to 2.5 GPa and hardness up to 300 MPa) were analyzed by microstructure (grain boundaries and homogeneity) and exterior factors (e.g. thickness). Overall, this study provides a new approach for tailoring the microstructures and mechanical properties of HEAs via melt spinning technique. The HEA ribbons present a novel form that could potentially broaden the scope of applications for these materials.