Estudo do efeito da adição do elemento prata em ligas quasicristalinas de Al-Cu-Fe em suas propriedades microestruturais

Abstract

The advance in research into metallic materials and their alloys has been remarkable in the last two decades, driven by the need to improve characteristics and optimize production costs. In this context, quasicrystals (QC) emerge, metal alloys with long-range ordered structures, but of short periodicity, which have tribological properties similar to those of ceramic materials and prove to be extremely fragile. The introduction of a fourth element into a QC alloy, such as silicon, e.g. stabilises the icosahedral phase, which is aperiodic in all directions. In this study, the impact of the addition of silver on the microstructure of the quasicrystalline alloy Al62,3Cu25,5Fe12,2 was analyzed. The direct addition of silver to the alloy resulted in destabilization of the quasicrystalline phase. To mitigate this, silver was added to replace copper, in the proportions of 0.5%, 1.0%, and 2.5%, resulting in the composition Al65Cu15-xFe12Agx (where x=0, 0.5, 1.0, 2.5, and 10). It was observed that 10% of silver destabilized the quasicrystalline phase, with a predominance of β and Ag2Al phases. With 0.5% and 1.0% silver, the quasicrystalline phase remained stable, despite traces of Ag2Al. The composition with 2.5% silver remained balanced, with icosahedral and Ag2Al quasicrystalline phases stable after 24 hours of treatment. Silver is expected to provide self-lubrication, reducing friction, and antimicrobial action.