Solidification microstructure and properties of Ni(60-y)Fe20Co10Cr10Aly high-entropy alloys

Abstract

 A series of eutectic high-entropy alloys Ni_(60-y)Fe₂₀Co₁₀Cr₁₀Al_y (y = 0, 5, 10, 15, 20, 25) were synthesized via non-consumable vacuum melting, followed by investigation into their solidification microstructures and compression properties. The research results reveal that the solidification microstructures transition from a well-distributed FCC phase (y-0, y-5) to a coarse FCC+B2 isometric crystal structure (y-10), subsequently to a primary FCC phase with a (FCC+B2) eutectic structure (y-15), succeeded by a predominant B2 phase with a (FCC+B2) eutectic microstructure (y-20), and ultimately to a BCC+B2 biphasic structure characterized by periodic braided sheets (y-25). The FCC phase demonstrates a substantial concentration of Ni and Fe, the BCC phase shows substantial enrichment primarily in Fe and Cr, while the B2 phase exhibits significant enrichment in Ni and Al. As the Al content increases, the alloys exhibit higher strength but reduced plasticity. Specifically, alloys with y values of 20 and 25 exhibit yield strengths of 1012 MPa and 1477 MPa, respectively, coupled with remarkable plasticity of 41 and 23%, thereby demonstrating robust mechanical properties.