Electropulsing treatment-induced the enhanced recrystallization of deformed Al0.1CoCrFeNi high-entropy alloy at lower temperature

Abstract

It is urgent to explore an efficient treatment strategy to obtain characteristic microstructures for better mechanical properties of alloys in an era of energy shortage. Here, we investigated whether electropulsing treatment (EP-treatment) could efficiently manipulate the microstructural evolution of pre-deformed Al0.1CoCrFeNi HEA. Under the condition of EP-treatment, the temperature required for complete static recrystallization of Al0.1CoCrFeNi HEA is reached earlier at 590 °C. This temperature is significantly lower than the recrystallization temperature induced by conventional heat treatment. The preferred accumulation of dislocations at grain boundaries in EP-treated Al0.1CoCrFeNi HEA provides favorable conditions for the nucleation of static recrystallization. This is due to the increased vacancy concentration and defect mobility, which are activated by the additional driving force of the electromigration effect. Moreover, the enhanced dislocation mobility leads to an increased nucleation rate within a very short electrical pulse time, which consequently facilitates accelerated recrystallization at a lower temperature. In addition, the static recrystallization process was accompanied by the accelerated annihilation of dislocations and the decreased dislocation density, which is consistent with the results of the global GND density decreasing from 2.0 × 1013 m−2 to 1.6 × 1013 m−2.

Keywords

• Electropulsing treatment
• Al0.1CoCrFeNi high-entropy alloy
• Static recrystallization
• Variations of dislocations
• Geometrically necessary dislocation density