Investigations of Oxide Dispersoids and Annealing on Characteristics of AlCoCrFeNi2.1 Coatings and Bulks Prepared by Mechanical Alloying

Eutectic high-entropy alloy (EHEA) has an outstanding combination of high strength and excellent ductility due to its dual-phase structure. In this study, AlCoCrFeNi2.1 coatings on stainless steel substrates and bulk AlCoCrFeNi2.1 alloys were prepared by mechanical alloying (MA). The results show that EHEA coatings with a dual-phase microstructure of BCC-AlNi/FCC-CoCrFe were obtained. A long milling duration promotes a uniform microstructure and homogeneous distribution of composition in the EHEA coatings, increasing hardness. Furthermore, annealing treatment encourages the formation of Cr-rich phases and Al-rich oxides, which affect the mechanical properties of coatings and bulk materials. Additionally, the presence of oxide dispersoids can cause the embrittlement of materials due to the formation of Al-Y-O oxide pores, resulting in the degradation of the mechanical properties of materials.