Additive Manufacturing of High-Entropy Alloys by Laser Processing

Abstract

This contribution concentrates on the possibilities of additive manufacturing of high-entropy clad layers by laser processing. In particular, the effects of the laser surface processing parameters on the microstructure and hardness of high-entropy alloys (HEAs) were examined. AlCoCrFeNi alloys with different amounts of aluminum prepared by arc melting were investigated and compared with the laser beam remelted HEAs with the same composition. Attempts to form HEAs coatings with a direct laser deposition from the mixture of elemental powders were made for AlCoCrFeNi and AlCrFeNiTa composition. A strong influence of solidification rate on the amounts of face-centered cubic and bodycentered cubic phase, their chemical composition, and spatial distribution was detected for two-phase AlCoCrFeNi HEAs. It is concluded that a high-power laser is a versatile tool to synthesize interesting HEAs with additive manufacturing processing. Critical issues are related to the rate of (re)solidification, the dilution with the substrate, powder efficiency during cladding, and differences in melting points of clad powders making additive manufacturing processing from a simple mixture of elemental powders a challenging approach.

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

“…[124] The influence of Al/Ni ratio on the hardness of the DLDed AlFeCoCrNi HEA was investigated by Sistla et al [120] The hardness decreased from 670 to 149 Hv as the Al/Ni ratio decreased. [82] In contrast to similar mechanical properties observed in the DLDed HEAs and their arc melted counterparts, the EBMed HEAs generally showed much more superior mechanical properties in comparison to their arc melted counterparts. [120] In addition, the high Al content HEA was brittle, the equiatomic HEA was not tough enough to resist cracking and the high nickel content HEA was too soft.…”

“…Several pioneering investigations have been conducted and reported on the microstructure and phase formation of HEAs fabricated using these metal additive manufacturing techniques. [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. The microstructures were also compared to the same HEAs produced using conventional arc melting ( Figure 11).…”

“…For example, three alloys based on Al x CoCrFeNi HEA system with different molar fraction of Al (x ¼ 0.3, 0.6, and 0.85) were successful fabricated using DLD by Joseph et al [119] Three different microstructures FCC, FCC/BCC, and BCC can be produced by varying the Al content, for example, Widmanstatten microstructure was found in the fabricated Al x CoCrFeNi HEA specimens (x ¼ 0.6). [82] Some work has also been carried out to fabricate refractory MoNbTaW HEAs using DLD technique from an equimolar mixture of elemental powders. No apparent difference has been detected in both the FCC and BCC microstructures produced using DLD and arc melting.…”

“…[30,[82][83][84]103,106,108,111,118,120,123] Not only fully dense and crack free BMGs and HEAs have been achieved but also some of the metal additive manufacturing fabricated BMGs and HEAs show promising properties in comparison to their conventionally fabricated counterparts. [30,[82][83][84]103,106,108,111,118,120,123] Not only fully dense and crack free BMGs and HEAs have been achieved but also some of the metal additive manufacturing fabricated BMGs and HEAs show promising properties in comparison to their conventionally fabricated counterparts.…”

Slurry Erosion Behavior of AlxCoCrFeNiTi0.5 High-Entropy Alloy Coatings Fabricated by Laser Cladding

“…In addition, the coatings can be deposited in a few steps, which eliminates the influence of the substrate and allows gradual composition and property changes through the coating thickness [9]. These favorable advantages have made the laser-cladding alloy attractive among surface modification technologies.…”