Synthesis and properties of high-entropy CoCrFeNiMnWx alloys

Abstract

Compact samples and coatings from CoCrFeNiMnWx high entropy alloys (HEAs) powders synthesized by mechanical alloying followed by plasma spheroidization (PS) were obtained by directed energy dssssseposition (DED). The microstructure of CoCrFeNiMnWx samples obtained by DED represents a cast dendritic structure. The phase composition of all samples represents a solid solution with FCC lattice. The increase in the lattice parameter in the samples by 0.33–0.47% compared to the spheroidized powder is characteristic of all obtained alloys after DED. The lattice parameter of CoCrFeNiMnWx samples increases with increasing W content, which is associated with the formation of a highly entropic solid replacement solution. The hardness of the samples increased by 4.6% and 12.9% with the addition of W in amounts of 0.125 and 0.25 at. % to the CoCrFeNiMn HEA, respectively. Tungsten-doped alloy coatings have a higher bending strength than the CoCrFeNiMn alloy. With relatively similar ductility values, the CoCrFeNiMn alloy has a lower strength, which is insufficient to resist cracking when bent to an angle above 20–45°, depending on the bending direction.

Keywords

• High entropy alloys
• Direct laser metal deposition
• Mechanical properties
• Corrosion behavior