Effect of fabrication methods on microstructures, mechanical properties and strengthening mechanisms of Fe0.25CrNiAl medium-entropy alloy

The effect of fabrication methods on microstructures, mechanical properties, and strengthening mechanisms of high-entropy alloys has been systematically studied. In this work, a non-equiatomic Fe0.25CrNiAl medium-entropy alloy (MEA) was selected and fabricated by arc-melting, spark plasma sintering (SPS), and hot-press sintering (HPS). The results indicate that the fabrication method has little effect on the main phase compositions of Fe0.25CrNiAl MEA while marked impacts on microstructures, mechanical properties, and strengthening mechanisms. All alloys mainly consist of a disordered body-centered cubic (BCC) phase and an ordered body-centered cubic (B2) phase. However, the arc-melted alloy possesses a typical dendritic structure, while a speckle-like microstructure for the SPS-ed and HPS-ed alloys. Particularly the grain is refined dramatically by powder metallurgical methods of SPS and HPS. The yield strength of powder metallurgical alloys is over 400 MPa higher than that of arc-melted alloy, and without sacrificing the ductility (similar to 30%). The strengthening mechanism analysis demonstrates that precipitate strengthening plays a significant role for arc-melted alloy while grain boundary strengthening is the dominant strengthening mechanism for powder metallurgical alloys. The Fe0.25CrNiAl MEAs by powder metallurgy achieve a trade-off between high strength and strain-to-failure, which suggests that the method is available for improving the mechanical properties of high-entropy alloys. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The effect of fabrication methods on microstructures, mechanical properties, and strengthening mechanisms of high-entropy alloys was systematically studied. Different fabrication methods have little effect on the main phase compositions of Fe0.25CrNiAl MEA, but significant impacts on microstructures, mechanical properties, and strengthening mechanisms were observed.