Obtaining Fe-35%Co alloys (% in mass) with Cr addition: survey of magnetic properties

• Grant number: 22/08992-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2022
• End date: November 30, 2023
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Cristina Bormio Nunes
• Grantee: Iris Braga Silva
• Host Institution: Escola de Engenharia de Lorena (EEL). Universidade de São Paulo (USP). Lorena , SP, Brazil
• Associated scholarship(s): 22/15322-2 - Magnetomechanical behavior of Fe-35%Co alloys (% in mass) with addition of 0.5 and 0.7% of Cr, BE.EP.IC

Abstract

There are practically no scientific studies published on Fe-Co alloys with lower amounts of Co than the equiatomic one. Everything that was developed in relation to these alloys was done by the industry, which does not provide data from the research carried out. These Fe-Co alloys with lower amounts of Co (27 < %Co < 35) are relevant to be studied, as they have high saturation magnetizations, high Curie temperatures, and are cheaper, as they have less cobalt. Considering only raw material prices, a ton of Fe-Co equiatomic alloy costs about 30% and 40% more than alloys with 35% and 30% Co, respectively. The price of Co per ton is 75000 USD, and for the iron contained in iron ore 260 USD. Therefore, we understand that it is important that Fe-Co alloys with a lower value of Co than the equiatomic alloy are revisited and studied more in-depth and in a systematic way, making the correlation of materials science/engineering with the physical properties of the material. This understanding may help in the future in some alloy formulation that allows magnetic and mechanical performance improvement of these materials. Consequently, the use of these materials in electrical machines will lead to greater energy efficiency, and urgent demand in a world lacking in energy. In particular, the demand for energy efficiency applies to electric cars and aircraft. For the present project, we chose as the object of study the Fe-Co alloy with 35% by mass of Co with the addition of Cr. One of the reasons for this choice is that the alloy with 35% Co, compared to the alloy with 30% Co, which we are already studying in another project, may have an increase in permeability with only an increase of 5% Co, as this increase causes a sharp drop in K1, the first anisotropic constant, which will cause the anisotropic field to decrease. The addition of Cr is performed to improve the ductility of the alloy and the effect of this addition on the magnetic properties of the material will also be analyzed.(AU)