Effect of the Annealing Treatment on the Microstructure, Microhardness and Corrosion Behaviour of Al_0.3CrFe_1.5MnNi_0.5 High-Entropy Alloys

Abstract:

In this study, an Al_0.3CrFe_1.5MnNi_0.5 high entropy alloy was synthesized by arc-melting in Ar. The as-cast alloy ingot was heat treated for 8 h at 650-750°C and then cooled in furnace to investigate the effects of age treatment on the microstructure, hardness and corrosion behaviour. The microstructure of as-cast sample has a typical rich-Cr BCC structure of dendrites, rich-Ni FCC interdendrite phases and a small fraction of cross-like rich-Ni FCC phase within the majority dendritic structure. During annealing treatment at 650°C, the cross-like FCC phase (β-FCC) gradually decreased, dendritic rich-Cr BCC phase transfers to Cr₅Fe₆Mn₈ phase, and the AlNi phase precipitated within the matrix dendrites. The interdendritic β₁-FCC phases gradually decomposed and transfers to second-phase (β₂ FCC), and the AlNi precipitated phase coarsen during annealing at 750°C. In addition, Cr₅Fe₆Mn₈ phase gradually transfers to rich-Cr BCC phase during slow-cooling process. These precipitation phases in the grain matrix are the main age hardening mechanism. The potentiodynamic polarization of the Al_0.3CrFe_1.5MnNi_0.5 high entropy alloys, obtained in 3.5% NaCl solutions, clearly revealed that the corrosion resistance increases and the passive region decreases as annealing temperature increasing.

• Periodical: Advanced Materials Research (Volume 748)
• Pages: 79-85
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.748.79
• Online since: August 2013
• Authors: L.C. Tsao, C.S. Chen, Kuo Huan Fan, Yen Teng Huang
• Keywords: Annealing, Corrosion Behavior, High-Entropy Alloys, Microhardness, Microstructure

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