Evolution of Microstructure and Mechanical Properties of a Novel CoCrFeNi2(TiSi)0.7 Eutectic High‐Entropy Alloys under Different Annealing Conditions

Eutectic high-entropy alloys (EHEAs), with good castability, compositional homogeneity, and outstanding properties, are becoming hotpots in materials field. It is worth noting that most reported EHEAs are based on expensive and high density of metal elements, such as Hf, Zr, Ta, Nb, W, and Pd, which increase the overall cost and quality. Herein, by selecting the cost-effective and low-density of Ti and Si as eutectic forming elements, a novel CoCrFeNi2(TiSi)0.7 EHEA with face-centered-cubic (FCC) + M16Ti6Si7-type silicide is designed and prepared. The evolution of microstructure and mechanical properties is investigated under different annealing conditions. The CoCrFeNi2(TiSi)0.7 EHEA shows excellent high-temperature mechanical properties. At 800 °C, the as-cast and annealed samples do not fracture under a compressive strain exceeding 50%. In particular, a long period of high-temperature annealing dramatically increases the high-temperature yield strength from 510 to 703 MPa, which exceeds that of most reported EHEAs and some refractory high-entropy alloys.