Propriedades magnéticas e resistência à corrosão de ligas com múltiplos componentes principais do sistema CuFeMnNiSnTi
Data
2023-04-27
Autores
Silva, Leandro Santos da 
Orientadores
Silva, Ricardo Alexandre Galdino da
Tipo
Tese de doutorado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
O surgimento das chamadas ligas de alta entropia elevaram expressivamente o número de possibilidades para obtenção de novos materiais com diferentes aplicações, viabilizando sistemas anteriormente inviáveis ou pouco explorados. Assim como as ligas de alta entropia, sistemas com múltiplos componentes principais ou ligas quimicamente complexas são sistemas que apresentam um elevado número de elementos de liga principais. Esta nova abordagem no estudo de materiais metálicos, exige a utilização cada vez mais constante de ferramentas de design, assim como o uso de aprendizado de máquina para direcionar os estudos de sistemas metálicos mais promissores. Neste trabalho, os efeitos dos teores de Cu, Ti e Sn na composição de fases e nas propriedades eletroquímicas e magnéticas em ligas multicomponentes do sistema CuFeMnNiSnTi foram avaliados utilizando-se microscopia óptica, microscopia eletrônica de varredura, espectroscopia por dispersão de energia de raios X, difratometria de raios X, medidas de magnetização em função do campo aplicado e da temperatura, polarização linear em solução de NaCl 1,0 mol L-1, análise termogravimétrica, calorimetria exploratória diferencial e análise térmica diferencial. A variação dos teores de Cu, Ti e Sn promoveu modificações na composição de fases das ligas estudadas com efeitos diretos sobre suas propriedades magnéticas e eletroquímicas. A liga CuFeMnNiSnTi apresentou três fases em seu estado bruto de fusão: os compostos Ti(Fe,Ni)2Sn, (Fe,Mn)2Ti e (Cu,Mn,Ni)3Sn, o que lhe conferiu magnetização de saturação igual a 22,5 emu g-1. Na ausência de Sn foram formadas as fases (Cu,Mn,Ni) e NiTi e uma elevada fração relativa da fase (Fe,Mn)2Ti se comparada à liga CuFeMnNiSnTi, mas em sua presença a formação das fases Ti(Fe,Ni)2Sn e (Cu,Mn,Ni)3Sn foi observada. A presença do elemento Ti em ligas do sistema CuFeMnNiSnTi conduziu à formação das fases (Fe,Mn)2Ti e Ti(Fe,Ni)2Sn, mas em sua ausência soluções sólidas de ferro foram formadas em conjunto com o composto (Cu,Mn,Ni)3Sn, presente em todas as ligas com variação do teor de titânio. Ao avaliar os efeitos da variação do teor de Cu em ligas do sistema de interesse, verificou-se que em sua ausência apenas os compostos Ti(Fe,Ni)2Sn e (Fe,Mn)2Ti foram formados. Pela adição de cobre, a formação do composto (Cu,Mn,Ni)3Sn foi obtida com aumentos de sua fração proporcionais ao teor de cobre na liga. O aumento do teor de Sn e Cu, e a redução do teor de Ti levaram aos maiores valores de magnetização máxima à temperatura ambiente. Em todos os casos o aumento de magnetização de saturação foi associado à presença da fase (Cu,Mn,Ni)3Sn. O segundo maior valor de magnetização de saturação na temperatura ambiente (40 emu g- 1), dentre as ligas estudadas, foi obtido para a liga CuFeMnNiSn com aproximadamente 75% da liga formada pelo composto (Cu,Mn,Ni)3Sn. Esse valor só foi superado pela adição de Co à liga CuFeMnNiSn, levando a uma magnetização máxima de 80 emu g-1 na temperatura ambiente. Todos os materiais estudados apresentaram resistência à corrosão inferior ao aço inoxidável 304. A redução do teor de estanho levou a valores da densidade de corrente de corrosão próximos ao do aço inoxidável 304, mas a estabilidade da camada passiva nas composições estudadas foi muito inferior ao material de referência. No entanto, a redução do teor de titânio e o aumento do teor de cobre levam a valores de densidades de corrente de corrosão menores, ou seja, uma maior resistência à corrosão. O isolamento do composto (Cu,Mn,Ni)3Sn foi possível diante da remoção do ferro com o estudo da liga CuMnNiSn.
The high-entropy alloys arising increased the possibilities for new materials obtention on different applications, which made possible the proposal of new materials for unsolved or poorly explored challenges. Complex concentrated alloys and multi-principal elements alloys as well are systems that show a high number of main alloying elements. This new approach on metallic materials study requires the use of design tools and machine learning as well, to provide directions to achieve promising metallic systems. In this study, the effects of Cu, Ti, and Sn content on the phases composition, electrochemical, and magnetic properties in the multicomponent CuFeMnNiSnTi system were evaluated using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, magnetic measurements as function of the applied field and temperature, linear polarization in NaCl 1.0 mol L-1 solution, thermogravimetric analysis, differential scanning calorimetry, and differential thermal analysis. The changes on Cu, Ti and Sn content promoted the phase composition change in the studied alloys with effects on the magnetic and electrochemical properties. The CuFeMnNiSnTi alloy had three phases in the as-cast condition: the Ti(Fe,Ni)2Sn, (Fe,Mn)2Ti, and (Cu,Mn,Ni)3Sn compounds, which promoted the saturation magnetization of 22.5 emu g-1. In the absence of Sn, the (Cu,Mn,Ni) and NiTi phases were formed with a high fraction of the (Fe,Mn)2Ti compound considering CuFeMnNiSnTi as reference, but in the presence of tin the Ti(Fe,Ni)2Sn and (Cu,Mn,Ni)3Sn phases were found. The titanium presence in the CuFeMnNiSnTi system induced the phase formation of (Fe,Mn)2Ti and Ti(Fe,Ni)2Sn, but without Ti, iron solid-solutions were found with the (Cu,Mn,Ni)3Sn compound, which was present in all CuFeMnNiSnTix alloys. During the evaluation of the effects of copper content in the selected system, it was found that in the copper absence only the Ti(Fe,Ni)2Sn and (Fe,Mn)2Ti compounds were formed. The (Cu,Mn,Ni)3Sn phase formation was obtained by the copper addition, and its fraction increased with the copper content. The increase on Sn and Cu content and the reduction of Ti content promoted higher magnetization values at room temperature. In all studied alloys, the magnetization increase was associated with the presence of (Cu,Mn,Ni)3Sn phase. The second highest value of magnetization at room temperature (40 emu g- 1), among the studied alloys, was found in the CuFeMnNiSn alloy that presented at about 75% phase fraction for the (Cu,Mn,Ni)3Sn compound. This value was only improved by the Co addition to the CuFeMnNiSn alloy, which presented a maximum magnetization of 80 emu g-1 at room temperature. All studied materials were less corrosion resistant than the SS 304. The reduction of tin content reduced the density of corrosion current to values near to that found for the SS 304, but with smaller stability of the passive layer in all compositions. Nonetheless, the reduction of titanium content and the increase of the copper content led to smaller corrosion current density values, i. e., a higher corrosion resistance. The isolated synthesis of the (Cu,Mn,Ni)3Sn compound was only possible by the iron removal and the study of the CuMnNiSn alloy.
The high-entropy alloys arising increased the possibilities for new materials obtention on different applications, which made possible the proposal of new materials for unsolved or poorly explored challenges. Complex concentrated alloys and multi-principal elements alloys as well are systems that show a high number of main alloying elements. This new approach on metallic materials study requires the use of design tools and machine learning as well, to provide directions to achieve promising metallic systems. In this study, the effects of Cu, Ti, and Sn content on the phases composition, electrochemical, and magnetic properties in the multicomponent CuFeMnNiSnTi system were evaluated using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, magnetic measurements as function of the applied field and temperature, linear polarization in NaCl 1.0 mol L-1 solution, thermogravimetric analysis, differential scanning calorimetry, and differential thermal analysis. The changes on Cu, Ti and Sn content promoted the phase composition change in the studied alloys with effects on the magnetic and electrochemical properties. The CuFeMnNiSnTi alloy had three phases in the as-cast condition: the Ti(Fe,Ni)2Sn, (Fe,Mn)2Ti, and (Cu,Mn,Ni)3Sn compounds, which promoted the saturation magnetization of 22.5 emu g-1. In the absence of Sn, the (Cu,Mn,Ni) and NiTi phases were formed with a high fraction of the (Fe,Mn)2Ti compound considering CuFeMnNiSnTi as reference, but in the presence of tin the Ti(Fe,Ni)2Sn and (Cu,Mn,Ni)3Sn phases were found. The titanium presence in the CuFeMnNiSnTi system induced the phase formation of (Fe,Mn)2Ti and Ti(Fe,Ni)2Sn, but without Ti, iron solid-solutions were found with the (Cu,Mn,Ni)3Sn compound, which was present in all CuFeMnNiSnTix alloys. During the evaluation of the effects of copper content in the selected system, it was found that in the copper absence only the Ti(Fe,Ni)2Sn and (Fe,Mn)2Ti compounds were formed. The (Cu,Mn,Ni)3Sn phase formation was obtained by the copper addition, and its fraction increased with the copper content. The increase on Sn and Cu content and the reduction of Ti content promoted higher magnetization values at room temperature. In all studied alloys, the magnetization increase was associated with the presence of (Cu,Mn,Ni)3Sn phase. The second highest value of magnetization at room temperature (40 emu g- 1), among the studied alloys, was found in the CuFeMnNiSn alloy that presented at about 75% phase fraction for the (Cu,Mn,Ni)3Sn compound. This value was only improved by the Co addition to the CuFeMnNiSn alloy, which presented a maximum magnetization of 80 emu g-1 at room temperature. All studied materials were less corrosion resistant than the SS 304. The reduction of tin content reduced the density of corrosion current to values near to that found for the SS 304, but with smaller stability of the passive layer in all compositions. Nonetheless, the reduction of titanium content and the increase of the copper content led to smaller corrosion current density values, i. e., a higher corrosion resistance. The isolated synthesis of the (Cu,Mn,Ni)3Sn compound was only possible by the iron removal and the study of the CuMnNiSn alloy.