First demonstration of promising selective electron beam melting method for utilizing high-entropy alloys as engineering materials

• We succeeded in applying selective electron beam melting to the AlCoCrFeNi high-entropy alloy.
• The mechanical properties of the molds were far superior to those of the corresponding castings.
• The ductility in particular was remarkably enhanced by selective electron beam melting.
• The fracture strength was above 1400 MPa, which was more than six times higher than that of SUS304.

High-entropy alloys (HEAs) are equiatomic, multi-element systems that contain five or more principal elements and have unique and excellent properties. However, it is difficult to overcome the inherent complexity and high levels of control required to produce homogeneous alloys industrially using a conventional casting method. We applied an additive manufacturing technique involving the use of selective electron beam melting (SEBM), which can facilitate a high level of local process control and generate rapid solidification cooling rates. The mechanical properties of the equiatomic AlCoCrFeNi HEA molds produced by SEBM were far superior to those of the corresponding castings. The ductility in particular was remarkably improved. The fracture strength was above 1400 MPa, which was more than six times higher than that of SUS304, a conventional engineering material. We succeeded in demonstrating for the first time that SEBM is a promising manufacturing process for utilizing HEAs as engineering materials.