Estudo analítico do diagrama de fases da liga Fe-Al através da técnica do operador diferencial

• Ano de defesa: 2009
• Autor(a) principal: Daniele Alves Dias
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Teoria de campo efetivo-EFT; Modelo de Ising; Ligas de ferro-alumínio; Diagrama de fase; Teoria de campo efetivo; Física
• Link de acesso: http://hdl.handle.net/1843/ESCZ-7YSGRE

In this work we study the ferromagnetic Ising model, in its pure and diluted versions, on several hypercubic lattices. We use the effective field theory (EFT) based on the differential operator technique. We consider exchange and superexchange interactions on the site diluted systems, while we only consider exchange interaction on the bond diluted systems. We used one and two site cluster approximations and we obtained the magnetization behavior as a function of the reduced temperature as well critical reduced temperature behavior as a function of the dilution concentration. The results were compared with the exacts ones, when available, and with the results obtained from the Bogoliubov inequality. We applied this model in the description of the thermodynamics properties of Fe-Al alloys. The experimental phasediagram were adjusted with the theoretical parameters. Reasonable fittings have been obtained, however not so different from those previously obtained from other approximate techniques.