Effect of Solidification Rate on the Microstructure and Strain-Rate-Sensitive Mechanical Behavior of AlCoCrFeNi High-Entropy Alloy Prepared by Bridgman Solidification

Abstract

AlCoCrFeNi high-entropy alloys (HEAs) were prepared by Bridgman solidification with different solidification rates, and the mechanical behavior of the HEAs was investigated over a wide strain rate range (∼10⁻³∼10³ s⁻¹). Microstructure observations suggest that, with increasing solidification rate, the microstructure evolves from coarse columnar grains to fine equiaxed ones. Through compression tests under both quasi-static and dynamic strain rates, the AlCoCrFeNi HEAs were found to possess positive strain-rate sensitivity (SRS), and the HEA with lower solidification rate exhibits higher SRS, which are attributed to the coarse grain size.

Fig. 1 Optical micrographs of the AlCoCrFeNi HEA by Bridgman solidification: (a) H₂₀₀ alloy; (b) H₁₂₀₀ alloy; (c) H₂₄₀₀ alloy; (1) cross section; (2) longitudinal section.