Microstructural development and mechanical behavior of a near-eutectic high entropy alloy Al1.8CrCuFeNi2 fabricated by hot isostatic pressing

Abstract

In this study, a near-eutectic high entropy alloy Al1.8CrCuFeNi2 was processed by hot isostatic pressing (HIP). It is shown that the as-HIPed alloy demonstrates excellent formability and shows uniform and refined B2 grains. Large Cr0.7Fe0.3 precipitates were found at the grain boundaries while nano-sized Cu, Cu3Ni and Fe–Cr particles were uniformly distributed within the grain interior. The fine structure and various precipitates lead to high compressive strength of ∼1800 MPa and good hardness of ∼470 HV. B2 matrix and intergranular Cr0.7Fe0.3 deformed mainly via dislocation slipping while intragranular Fe–Cr particles showed complex interaction with dislocations to impede dislocation motion. Moreover, the Fe–Cr nano-precipitates also deformed with the formation of stacking faults, which may further enhance the alloy. The high strength could be due to the activation of multiple deformation and strengthening mechanisms and mainly attributed to the precipitate strengthening.