A comparative study on interfacial reactions involving molten aluminum in contact with a multicomponent FeCrNiCoMnAl high entropy alloy and a 2205 duplex stainless steel

A multicomponent FeCrNiCoMnAl High Entropy Alloy (HEA) and a 2205 duplex stainless steel (DSS) were immersed in molten Al at 700° C for various periods of time, and the respective interfacial reactions were investigated. Material characterization on two solid phases showed that the BCC phase in the FeCrNiCoMnAl HEA was rich in Ni and Al elements while the FCC phase in this HEA was rich in Fe and Cr elements. These elemental enrichment results were in contrary to those in the dual phases of the 2205 DSS. After immersion of the HEA in a 700 °C Al melt for 1 h, a continuous thin layer consisting of a nanocrystalline FCC phase was found in the HEA/Al interface. The crystallinity of the reaction product increased with prolonged immersion time, accompanying with increasingly thickening interlayer. In contrast, a thicker FeAl3 intermetallic layer was formed in the DSS/Al interface. This layer further developed into a complex structure consisting of an inner Fe₂Al ₅ and an outer FeAl₃ layers. Finally, the metal loss rate of the FeCrNiCoMnAl HEA in molten Al was slower than that of the 2205 DSS.