Estudo do efeito do nióbio como quarto elemento da liga icosaedral quasicristalina Al-Cu-Fe

• Ano de defesa: 2025
• Autor(a) principal: Costa, Ingrid Mayara Figueiredo da
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Engenharia Mecânica; Programa de Pós-Graduação em Engenharia Mecânica; UFPB
• Palavras-chave em Português: Ligas quasicristalinas; Al-Cu-Fe-Nb; Fase Al3Nb; Quasicrystalline alloys; Al3Nb phase; CNPQ::ENGENHARIAS::ENGENHARIA MECANICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/36889

The development of novel metallic alloys is essential to meet the increasing demands of modern industry. In this context, the discovery of quasicrystalline alloys represents a significant advancement, as these structures exhibit unique properties, making them promising for coating applications. Continuous research on these alloys opens new avenues for technological innovation and industrial process optimization. This dissertation investigates the impact of niobium addition on the structural stability and microstructural properties of quasicrystalline alloys in the Al-Cu-Fe system. Thermodynamic analyses via PANDAT revealed that the I-Qc quasicrystalline phase is progressively replaced by approximant phases and the Al3Nb phase as the Nb content increases. X-ray diffraction (XRD) results indicated that the Al3Nb phase forms at Nb concentrations as low as 0.5%, with progressive growth as Nb content increases. Heat treatment favored the stability of the quasicrystalline phase up to 2.0% Nb; however, for higher Nb levels, the stabilization of the Al3Nb phase competed for the available aluminum, reducing the quasicrystalline phase fraction. The addition of Nb directly influenced the melting temperature of the alloys, progressively increasing it due to the formation of the Al3Nb phase. The quasicrystalline phase predominated in alloys with up to 2.0% Nb, but its stability decreased at higher Nb levels due to Al3Nb formation. Electrochemical tests indicated that heat treatment improves stability for certain compositions, depending on the Nb content. Alloys with 5.0% Nb exhibited the lowest corrosion current values, suggesting a threshold at which Nb optimizes corrosion resistance without compromising passive layer stability. The results demonstrate that controlled niobium addition can optimize the properties of Al-Cu-Fe-Nb quasicrystalline alloys, enabling their application in advanced coatings and high-performance structural components.