Estudo das reações em fase sólida de ligas CuAlAg
Data
2022-06-22
Autores
Oliveira, Ana Carolina Gonzaga de 
Orientadores
Silva, Ricardo Alexandre Galdino da
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Neste trabalho as transições de fase que ocorrem em ligas metaestáveis de CuAlAg foram estudadas. As ligas foram inicialmente submetidas a têmpera e posteriormente aquecidas para determinação das transições de fase dos materiais. Diferentes composições, partindo da liga sem adições de prata até o limite de 5,4%at.Ag, foram devidamente analisadas por diferentes técnicas experimentais. Os efeitos da variação da concentração de Ag sobre as transformações de fase e as propriedades das ligas Cu79,3Al20,7, Cu77,8Al20,9Ag1,3, Cu76,3Al21,1Ag2,6, Cu74,7Al21,3Ag4,0 e Cu73,1Al21,5Ag5,4 (%at.) foram estudadas utilizando-se as técnicas de microscopias óptica (MO), microscopia eletrônica de varredura (MEV), espectroscopia por dispersão de energias de raios X (EDX), calorimetria exploratória diferencial (DSC) e difratometria de raios X (DRX). As imagens obtidas por microscopia óptica mostram que a presença da prata parece promover um deslocamento no equilíbrio de fases para teores mais elevados de Al, permitindo o convívio das fases martensíticas β’ e β1’. A solubilidade da prata na matriz martensítica está em torno de 2,6%atAg e uma microestrutura eutética derivada do sistema de Ag e Al parece ser produzida a partir de 2,6%atAg. Os ensaios de difratometria de raios X confirmaram a presença da fase Ag2Al, que é um dos produtos da decomposição eutética do canto rico em Al do diagrama de fases Ag-Al. A liga Cu79,3Al20,7 mostrou cinco reações em fase sólida que foram alteradas com a adição de prata.
In this work, the phase transitions that occur in metastable CuAlAg alloys were studied. The alloys were initially subjected to quenching and then heated to determine the phase transitions of the materials. Different compositions, starting from the alloy without additions of silver up to the limit of 5,4%at.Ag were analyzed by different experimental techniques. The effects of the variation of the Ag concentration on the phase transformations and the properties of the Cu79,3Al20,7, Cu77,8Al20,9Ag1,3, Cu76,3Al21,1Ag2,6, Cu74,7Al21,3Ag4,0 e Cu73,1Al21,5Ag5,4 alloys (%at.) were studied using optical microscopy (OM), scanning electron microscopy (SEM), X-ray energy scattering spectroscopy (EDX), differential scanning calorimetry (DSC), and X-ray diffraction patterns (DRX). The images obtained by optical microscopy showed that the presence of silver seems to promote a shift in the phase equilibrium towards higher levels of Al, allowing the coexistence of the β’ and β1’ martensitic phases. The solubility of silver in the martensitic matrix is around 2.6%atAg and a eutectic microstructure derived from the Ag and Al system seems to be produced from 2.6%atAg. X-ray diffractometry tests confirmed the presence of the Ag2Al phase, which is one of the eutectic decomposition products of the Al-rich zone of the Ag-Al phase diagram. The Cu79,3Al20,7 alloy showed five solid-phase reactions that were altered with the addition of silver.
In this work, the phase transitions that occur in metastable CuAlAg alloys were studied. The alloys were initially subjected to quenching and then heated to determine the phase transitions of the materials. Different compositions, starting from the alloy without additions of silver up to the limit of 5,4%at.Ag were analyzed by different experimental techniques. The effects of the variation of the Ag concentration on the phase transformations and the properties of the Cu79,3Al20,7, Cu77,8Al20,9Ag1,3, Cu76,3Al21,1Ag2,6, Cu74,7Al21,3Ag4,0 e Cu73,1Al21,5Ag5,4 alloys (%at.) were studied using optical microscopy (OM), scanning electron microscopy (SEM), X-ray energy scattering spectroscopy (EDX), differential scanning calorimetry (DSC), and X-ray diffraction patterns (DRX). The images obtained by optical microscopy showed that the presence of silver seems to promote a shift in the phase equilibrium towards higher levels of Al, allowing the coexistence of the β’ and β1’ martensitic phases. The solubility of silver in the martensitic matrix is around 2.6%atAg and a eutectic microstructure derived from the Ag and Al system seems to be produced from 2.6%atAg. X-ray diffractometry tests confirmed the presence of the Ag2Al phase, which is one of the eutectic decomposition products of the Al-rich zone of the Ag-Al phase diagram. The Cu79,3Al20,7 alloy showed five solid-phase reactions that were altered with the addition of silver.