Influence of quasi-crystal particles and processing condition on microstructure and tensile properties of a selective laser melted high entropy alloy

Quasi-crystal (QC) Al65Cu20Fe10Cr5 powder particles were added into CoCrFeMnNi high entropy alloy (HEA) and processed by selective laser melting (SLM) under different conditions with the aim of enhancing their strengths. It is shown that increased energy density leads to increased grain size and texture in the SLMed HEA but does not cause significant influence on tensile properties. With the addition of QC particles, the microstructure and tensile properties highly depend on input energy density. Thus, HEA-10 wt% QC samples made between 55.6 J/mm3 and 92.6 J/mm3 are dominated by dispersive columnar gamma grains and arc-shaped B2 phase and nano-sized Al2O3 particles while those made with high energy densities such as 133.3 J/mm3 contain mixed large vertical and horizontal columnar gamma grains but no B2 phase. The B2-containing HEA-10 wt% QC samples show remarkably enhanced yield strength and ultimate tensile strength, thanks to B2 and nano-sized Al2O3 particles acting as effective dislocation motion barriers. The B2-free HEA-10 wt% QC samples show reduced strengths which is attributed to their large and complex grain structure and dendritic structure.

Automated summary

Adding quasi-crystal (QC) powder particles to high entropy alloy (HEA) during selective laser melting (SLM) can enhance the strength of the alloy. The microstructure and tensile properties of the material depend on the input energy density. Optimal energy density can result in a superior microstructure with dispersive columnar gamma grains and arc-shaped B2 phase, while high energy densities can lead to an undesirable grain structure.