Estudo dos diagramas de fases Mn-Sn e Mn-Fe-Sn para aplicações em dispositivos termomagnéticos de conversão de energia térmica

• Ano de defesa: 2013
• Autor(a) principal: Felez, Marissol Rodrigues [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paul
• Palavras-chave em Português: Phase diagram of Mn-Sn phase diagram of Mn-Fe-Sn magnetic phase transitions; Intermetallic compounds; Diagrama de fases Mn-Sn; Diagrama de fases Mn-Fe-Sn; Transições de fase magnéticas; Compostos intermetálicos
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=95535; https://repositorio.unifesp.br/handle/11600/47550

Mn100-xSnx alloys systems (x = 3, 6, 12, 18, 21, 24, 27, 32, and 35), Mn2 and Mn3-xFexSn- xFexSn (x = 0.00, 0.25, 0.50 , 0.75, 1.00, 1.25) were prepared in the electric arc furnace and heat treated resistive furnace. The heat treatment was ten days at a temperature of 900 0C Mn3-xFexSn for the system and ten days at 800 0C for the other two systems. The merged and treated samples were analyzed by optical metallography, scanning with EDS compositional analysis via electron microscopy, X-ray diffraction (Rietveld method), differential scanning calorimetry and magnetization as a function of temperature and applied field. The results obtained for Mn100-xSnx system indicated deviations from the composition of Mn76Sn24 suggest instability and phase equilibrium of phases for the merged and treated as compounds studied Mn3Sn the left of the phase diagram of the Sn-Mn phase accepted in the literature. The analysis of the magnetic alloys Mn100-xSnx system to the fields of phases Mn3Sn Mn + and Mn2 + Mn3Sn-XSN indicated the possibility that the solubility range of phase 3: 1 may be significantly larger than that placed in the aforementioned diagram and has also shown that there may be transition temperature dependence of the antiferro-iron (or ferric) with the Sn content in this phase. The results for the ternary system phase showed a MnnFemSnp not mentioned in the literature. The magnetic analyzes indicated for Mn0,75Fe1,25Sn and Mn1,75Fe1,25Sn compounds, heat treated, Curie temperatures Tc = 361 K and Tc = 358 K, respectively. These alloys in particular should be used in thermomagnetic engines under development at the Laboratory of Mechanical Manufacturing and Materials UNIFESP.