The micro-mechanical behavior of Al 0.6 CoCrFeNi high-entropy alloy during tensile deformation was investigated using an in situ synchrotron-based high-energy X-ray diffraction technique. The alloy consisted of face-center-cubic (FCC) and body-center-cubic-based (BCC-based) structure accompanied by a small amount of  phase. The FCC phase yielded prior to the BCC-based phase during the tensile loading, and the BCC-based phase bore more stress partition during the plastic deformation stage in spite of only ~23% volume fraction. A reversible deformation-induced martensitic transformation from the BCC-based phase to orthorhombic phase was observed during the plastic deformation stage. The transformation preferentially occurred in the grains with an orientation of B-[001]//loading direction and B-[110]//transverse direction. The study characterized the micro-mechanical behavior

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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 (³10 ¹3 ³10 3 s ¹1). Microstructure observations suggest that, with increasing solidification rate, the microstructure evolves from coarse columnar grains to fine equiaxed ones. Through compression tests under both quasistatic 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.

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