Desenvolvimento de ligas quasicristalinas (AlCuFeCo) a partir de elementos precursores reciclados para uso potencial aplicações em engenharia

Abstract

The development of high-performance quasicrystalline alloys is traditionally associated with the use of high-purity raw materials, leading to increased costs and environmental impact. In this context, this thesis aimed to develop Al–Cu–Fe quasicrystalline alloys doped with Co using recycled precursors, and to evaluate their microstructural, mechanical, surface, and electrochemical performance in comparison with alloys produced from pure elements. Al₆₅Cu₂₂Fe₉Co₄ alloys were fabricated by conventional casting and subjected to heat treatments Characterization was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Vickers microhardness, wettability measurements (contact angle in distilled and saline water), and corrosion tests.XRD results confirmed the formation and stability of icosahedral (ψ) and decagonal (D) quasicrystalline phases under all investigated conditions, coexisting with β and β₂ and λ approximant phases. Heat treatment promoted the stabilization of the icosahedral phase in alloys produced from pure elements, while the decagonal phase remained more persistent in recycled alloys. EDS analyses indicated that microstructural evolution occurs through internal chemical redistribution, maintaining compositions within the quasicrystalline stability domain despite the presence of residual impurities. Microhardness measurements showed high and stable hardness values, with only minor variations. Wettability tests revealed consistently high contact angles, indicating low surface wettability typical of quasicrystalline materials..Overall, the results demonstrate that recycled precursors can be successfully employed to produce Al–Cu–Fe–Co quasicrystalline alloys with properties comparable to those obtained from high-purity raw materials, validating a sustainable and efficient processing route.