Development of cost-effective scrap-tolerant bulk-scale high entropy alloys

Abstract

Developing bulk high entropy alloys (HEAs) with good strength and ductility combinations is challenging. Many of the currently reported HEAs are prepared from pure metals. The current study selected a multicomponent CoCrFeMn alloy and prepared it using scrap, ferroalloys, and pure elements. Further improvement in the properties of as-cast alloys is done by minute solute addition. The Thermo-Calc® simulation studies identified the maximum amount of minute solute elements that can be added without any new phase formation. The studied master alloy and modified compositions show a multiphase structure with FCC and HCP phases. The detailed microstructural analysis confirms that the secondary dendritic arm spacing was reduced while adding trace elements, and Cu-containing alloys showed a reduction of ∼44.44 %. The effect of the casting condition was studied by varying the heat transfer condition via different mould geometries. The mechanical properties, such as the tensile test and Vickers microhardness, show remarkable improvement with minute additions of solutes and by varying heat transfer conditions. The master alloy and Cu containing alloy show a maximum strength of ∼429 MPa and ∼562 MPa, respectively. The Cu-containing alloy shows an outstanding strength-ductility combination, and the detailed TEM-STEM analysis confirms the formation of Fe-rich clusters and Cu-rich phases. The current study shows a cost reduction of ∼1/10 compared with the alloys formed by pure elements.