Tuning Mechanical Properties of High Entropy Alloys by Electro-Pulsing Method

The single-phase face-centered cubic (FCC) high entropy alloys (HEAs) with remarkable ductility but lower strength, limiting the engineering application in a wide range. The ductility-strength trade-off could be addressed by tuning the constituent and chemical composition to lower stacking fault energy (SFE) and introduce additional strain-hardening strategies. In this work, a series of non-equiatomic (Co 40 Fe 25 Cr 20 Ni 15 ) 95 Al 5 HEAs annealed by flash electro-pulsing treatments at different voltages, was prepared with the incorporation of deformation twining during plastic deformation. The 130 V-annealed sample demonstrated a good combination of tensile strength of 0.96 GPa and ductility of 16.5%, while the 150 V-annealed alloy showed dramatically increased ductility of 49.2%. The higher Hall-Petch coefficient k H ( K σy ) value of 341.6 (828.8) and the thinner deformation twins spacing was responsible for the improved tensile strength for 130 V-samples. Moreover, more stacking faults and deformation twins in 150 V-sample accommodated more plastic and delayed the fracture, resulting increased ductility. This work provides a fast-effective method to tune the mechanical properties of non-equiatomic HEAs by adjusting the annealing voltage and achieved in a minute, which might open the avenue for future industrial application.