Favorable property integration in high entropy alloys via dissimilar friction stir welding: A case study using Al0.3CoCrFeNi and Fe38.5Co20Mn20Cr15Si5Cu1.5 HEAs

Abstract

The advent of high entropy alloys (HEAs) enabled fine-tuning of the alloy composition from the vast compositional space to develop solid-solution alloys having good physical and mechanical properties. Each HEA composition is the culmination of careful alloy design strategy aimed at a specific property intended for a specific application that is achieved by microstructural alteration and/or activation of deformation mechanisms. Methods to integrate the favorable properties pertaining to each HEA potentially benefit alloy selection for structural applications. In this study, dissimilar friction stir welding (FSW) was performed using Al0.3CoCrFeNi HEA and Fe38.5Co20Mn20Cr15Si5Cu1.5 TRIP HEA to integrate the beneficial mechanical properties of both HEAs. Unlike fusion welding methods that lead to a weaker weld zone, dissimilar FSW of the HEAs resulted in a refined microstructure in the stir zone (SZ) with enhanced mechanical performance compared to both base materials and enabled promising property integration. Improved and integrated mechanical property achieved in SZ was correlated to the microstructure, existing recrystallization mechanisms, and active deformation mechanisms in both alloys.