Effect of dealloying process on the microstructure of intermetallic rapidly solidified ribbons

Abstract Four alloys with compositions referring to intermetallic compounds or decagonal quasicrystalline phases were manufactured using the melt spinning method. The obtained material was in the form of fragmented brittle ribbons, which, after pulverization, were applied as catalysts for the hydrogenation of phenylacetylene. Preliminary research on catalytic performance for all alloys indicated a potential for high activity in the reaction. A crucial role in the catalytic performance of material plays its specific surface area. One method that can be applied to increase the specific surface is the chemical treatment of the material. The best results were obtained with NaOH solution for the examined materials. The presented work aims to study the morphology of as-spun ribbons and ribbons after leaching with a selected time of exposition of the ribbon in an alkaline environment. Furthermore, energy dispersive spectroscopy  analysis was applied to verify the impact of leaching on the chemical composition of ribbons.

Summary Presented materials in the as-spun state had dense morphology in ribbon surface and cross-section. However, Al-Ni-Co alloy had fine pores near the free surface of the ribbon, and Al-Ni-Fe alloy revealed a multiphase structure also manifested in the complex morphology. Chemical treatment with the NaOH 2M solution led to the degradation of ribbon material, mostly along grain boundaries. The depth of reagent impact on morphology increases with the exposition time. The surface oxidation is clearly visible for alloys containing iron and, in several cases, cobalt. A significant dissolution is observed in the areas with morphology changed by reagent, and oxidation occurs. Further work will aim to reduce oxidation to obtain a material with the best possible properties for catalytic experiments. 

Acknowledgements: This work was financially supported by the National Science Centre (NCN) Poland within project No. 2021/41/N/ST8/02533

Presented at: 11th European School for Young Materials Scientists, NOVA University Lisbon, School of Science and Technology, Portugal, Caparica 27-28.09.2022