Formation mechanism of cellular structure of Ni32.5Co15Cr10Fe23Al17.5Mo1.5W0.5 eutectic high-entropy alloys by selective laser melting

Abstract

The extremely fast cooling rate of selective laser melting can significantly refine the lamellar structure of eutectic high-entropy alloys. However, extreme solidification conditions also promote the appearance of honeycomb-like cellular structures. Here, we show that the competitive growth of the primary phase and eutectic determines the formation of cellular structure. Our results demonstrated that the composition conditions of FCC-B2 eutectic formation are more severe at excessively high growth rates. Therefore, although increasing the cooling rate will significantly decrease the size of the cellular structure, it cannot change the morphology of the cellular structure of Ni32.5Co15Cr10Fe23Al17.5Mo1.5W0.5 hypereutectic alloy.

Keywords

• Cellular structure
• rapid solidification
• high entropy alloys
• microstructure evolution