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

Phase Stability of a Mechanically Alloyed CoCrCuFeNi High Entropy Alloy

“…[1][2][3][4][5][6] However, other two factors, such as enthalpy of mixing (DH mix ), and atomic size difference (d), are also dominant to predict the phase formation in HEA systems. [4] Bulk HEAs can be prepared using various experimental techniques, such as vacuum arc melting, [7,8] electron beam melting, [9,10] and powder metallurgy. [11,12] However, intermetallics phases and micro-segregation have been observed in many as-cast HEA alloys, due to longer expose time at high temperature.…”

Additive Manufacturing of Advanced Multi‐Component Alloys: Bulk Metallic Glasses and High Entropy Alloys

“…[120] Another systematic study was carried out by Ocelik et al focusing not only on the effects of laser processing parameters, but also the influence of Al concentration on the microstructure and phase formation of AlCoCrFeNi HEA. [121] It is noteworthy that compared to the top part of the EBM specimens, the bottom part had higher abundance ratio of both the equiaxed grains and the FCC crystals. The authors concluded that the success of the fabrication of HEAs using DLD technique depended on several materialsand processing-related parameters including in-take of particular powders, melting temperatures, laser beam traveling speed, and laser power density.…”

“…Al was found to cause the significant lattice strain, which resulted in ordering and spinodal decomposition reactions during cooling. [121] It was also pointed out that the segregation of Fe and Co as well as a fine structure with fluctuating element concentrations inside the grains were observed at the grain boundaries in the EBMed specimens and the casting specimens. [82] By conducting laser remelting experiments, the results showed the solidification rate had a strong influence on the amounts of FCC and BCC phases, their chemical composition and spatial distribution, for example, fast solidification substantially increases the preference for the BCC phase.…”

“…By decreasing the Al/Ni ratio, the solid solution transited from a BCC structure to a FCC structure and the lattice parameter increased from 0.288 to 0.357 nm. [121] It was found that the EBMed HEAs had a BCC and FCC structure while the raw powders and the casting specimen were all BCC single-phase structures (Figure 13a). Al was found to cause the significant lattice strain, which resulted in ordering and spinodal decomposition reactions during cooling.…”

“…[119] Similarly, the influence of Al/Ni ratio on the microstructure and phase formation in the DLDed Al x FeCoCrNi 2-x HEA by Sistla et al [120] It was found that the Al/Ni ratio had a profound effect on the microstructure and phase formation of the fabricated HEA ( Figure 12). [121][122][123] For example, Fujieda et al reported the successful fabrication of AlCoCrFeNi HEAs using EBM, which can enable a high level of local process control as well as fast cooling. The microstructure changed from dendritic to equiaxed and then to a columnar structure.…”