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Master's Dissertation
DOI
https://doi.org/10.11606/D.97.2021.tde-18012022-123336
Document
Author
Full name
Fernando Froes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Lorena, 2021
Supervisor
Committee
Nunes, Cristina Bormio (President)
Pacheco, Clara Johanna
Ghivelder, Luis
Landgraf, Fernando Jose Gomes
 
Title in Portuguese
Obtenção de ligas magnéticas de Fe0,70Co0,30, com adição de Nb e Ti: Estudo de propriedades físicas
Keywords in Portuguese
Campo Coercivo
Fe-Co
Fe-Co-Nb-Ti
Magnetostricção
Permeabilidade Magnética
Abstract in Portuguese
As ligas baseadas em ferro (Fe) e cobalto (Co) são ligas magnéticas macias com alta magnetização de saturação, alta temperatura de Curie, relativamente baixas anisotropia magnética e resistência elétrica. No presente estudo foram obtidas as ligas de Fe0,7Co0,3 (liga referência), (Fe0,7Co0,3)97Ti3, (Fe0,7Co0,3)98Nb2, (Fe0,7Co0,3)99Nb1, (Fe0,7Co0,3)95Ti3Nb2 e (Fe0,7Co0,3)96Ti3Nb1, com o intuito de se estudar separadamente os efeitos das adições de Ti e Nb à liga de Fe0,7Co0,3 na microestrutura e nas propriedades magnéticas. As amostras foram fundidas no forno a arco, recozidas, tendo sido obtidas a indução magnética, a permeabilidade magnética, a magnetostricção e a resistividade elétrica. Também foram feitas análises de microscopia eletrônica de varredura/EDS, difratometria de raios X e análise da dureza Vickers. O campo coercivo da liga Fe0,7Co0,3 foi reduzido com a adição de Ti e mais ainda com a subsequente adição de Nb à liga (Fe0,7Co0,3)97Ti3. Com relação à permeabilidade relativa, a adição de titânio à liga Fe0,7Co0,3 aumentou em 50% a permeabilidade magnética relativa inicial, enquanto a adição de nióbio e titânio reduziu-a em 76%. A resistividade da liga (Fe0,7Co0,3)97Ti3 aumentou com a adição de titânio e subsequente de Nb em 4 vezes em relação à liga (Fe0,7Co0,3). A indução de saturação e a magnetostricção da liga (Fe0,7Co0,3)97Ti3 reduziram se comparadas à da liga (Fe0,7Co0,3), o mesmo acontecendo para a liga (Fe0,7Co0,3)96Ti3Nb1 comparada à liga (Fe0,7Co0,3)97Ti3. A adição de Nb tem maior influência na redução de Bsat0,7Co0,3)97Ti3 foi a que apresentou aumento da permeabilidade magnética comparativamente a da liga Fe0,7Co0,3, tendo causado apenas uma pequena diminuição na magnetização de saturação. Houve também a diminuição da magnetostricção e um aumento incrível na resistividade da liga. Estes fatores são interessantes para a aplicação do material na forma de chapas em núcleos de motores e transformadores de alta performance, ou seja, que necessitam de alta indução magnética de saturação. Apesar da liga (Fe0,7Co0,3)97Ti3 não ter atingido a magnetização de saturação das ligas Fe-Co (50Co) e da liga comercial Fe49Co-2V (Permedur), a quantidade de Co é menor, o que confere ao material um menor custo.
 
Title in English
Obtention of magnetic alloys Fe0.70Co0.30 with Nb and Ti additions: Study of physical properties 2021
Keywords in English
Coercive field
Fe-Co
Fe-Co-Nb-Ti
Magnetic permeability
Magnetostriction
Abstract in English
Alloys based on iron (Fe) and cobalt (Co) are soft magnetic alloys with high saturation magnetization, high Curie temperature, relatively low magnetic anisotropy and electrical resistance. In the present study, Fe0.7Co0.3 (reference alloy), (Fe0.7Co0.3)97Ti3, (Fe0.7Co0.3)98Nb2, (Fe0.7Co0.3)99Nb1, (Fe0.7Co0.3)95Ti3Nb2 and (Fe0.7Co0.3)96Ti3Nb1 were produced, to study separately the effects of Ti and Nb additions to the Fe0.7Co0.3 alloy microstructure and magnetic properties. The alloys were produced by arc melting and were subsequently annealed. (Fe0.7Co0.3)97Ti3 and (Fe0.7Co0.3)96Ti3Nb1 alloys were also processed by hot rolling to get sheets. Measurements of magnetic induction hysteresis, magnetic permeability, magnetostriction and electrical resistivity were performed, as well as scanning electron microscopy / EDS analyzes, X ray diffractometry and Vickers. The coercive field of the Fe0.7Co0.3 alloy was reduced with the addition of 3 at. % of Ti and even more with the subsequent addition of Nb to the (Fe0.7Co0.3)97Ti3 alloy. Regarding the relative permeability, the addition of titanium to the Fe0.7Co0.3 alloy increased the initial relative magnetic permeability by 50%, while the addition of niobium and titanium reduced it by 76%. The resistivity of the alloy increased with the addition of titanium and subsequent Nb, about 4 times in relation to the Fe0.7Co0.3 alloy. Saturations induction and magnetostriction of the (Fe0.7Co0.3)97Ti3 alloy were reduced compared to the Fe0.7Co0.3 alloy and the same happened for the (Fe0.7Co0.3)96Ti3Nb1 alloy compared to the (Fe0.7Co0.3)97Ti3 alloy. The addition of Nb has a greater influence on the reduction of Bsat than the addition of Ti. Thus, through this study we concluded that the (Fe0.7Co0.3)97Ti3 alloy was the one that increased the magnetic permeability of Fe0.7Co0.3 alloy and caused a small decrease in the saturation magnetization. There was also a decrease in magnetostriction and an extraordinary increase in the resistivity of the alloy. These factors are interesting for the application of the material in the form of plates in motor cores and high-performance transformers, which require high magnetic saturation induction. In spite of the (Fe0.7Co0.3)97Ti3 alloy has not reached the saturation magnetization of the Fe-Co (50Co) alloy and the Fe49Co-2V commercial alloy (Permedur), the amount of Co is less, which gives the material a lower cost.
 
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EMD21001_C.pdf (5.73 Mbytes)
Publishing Date
2022-01-18
 
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