Effect of electric current pulse on microstructure and mechanical properties of AlCoCrFeNi2.1 eutectic high entropy alloy

In this work, the AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) was subjected to 800 V electric current pulse (ECP) with frequencies of 2, 5, 10, and 20 Hz during the solidification process, respectively. And the effect of the electric current pulse on the microstructure and mechanical properties of the AlCoCrFeNi2.1 EHEA was systematically investigated. The results showed that all the AlCoCrFeNi2.1 samples contained FCC and B2 two phases. In addition, the Cr-rich BCC precipitates in the B2 phase. And the morphology of the Cr-rich nanoscale precipitates is spherical and the number increases after applying the ECP. The Non-ECP, 2 Hz, 5 Hz, and 20 Hz samples exhibited a eutectic structure with a primary dendrite of FCC phase + L12 precipitates. And the ECP spheroidized the primary phase morphology. With the increase of the pulse frequency, the flat eutectic layer spacing (λ) decreases, while the number of flat eutectic layer increased. Moreover, EDS results indicated that the ECP makes the more uniform distribution of the elements in different regions. With the increase of pulse frequency, the Vickers hardness gap between the vertical and parallel planes of the sample decreases. The 20 Hz sample exhibited the best mechanical properties with the tensile fracture strength of 1080 MPa and tensile fracture strain of 24.9%. This indicated that the ECP is an effective method to improve the mechanical properties of the AlCoCrFeNi2.1 EHEA. •ECP technology is applied to AlCoCrFeNi2.1 for the first time.•The influence mechanism of ECP on the structure and properties of AlCoCrFeNi2.1 was comprehensively studied.•The deformation behavior and mechanism of AlCoCrFeNi2.1 after ECP treatment were studied.