Design Parameters for Nanostructured Soft Magnetic Alloys

Magnetic properties of some nanocrystalline soft magnetic alloys are evaluated by means of a model obtained from literature. The influence of alloy elements in grain diameter, crystalline fraction and anisotropies are investigated in order to obtain information for the design of nanocrystalline soft magnetic materials. The study concerns materials with nanocrystalline composition of Fe, Fe-Si, Fe-Si-Al, and Fe-Ge, and is complemented with alloys containing nanocrystals of Fe and Fe-Co from literature. Results indicate that the reduction of grain diameter in Fe-based nanocrystal alloys is the main challenge to enhance the soft magnetic properties, when induced anisotropies are suppressed. For Fe-(Si,Al,Ge)-based nanocrystals, it is necessary to obtain a good balance of the magnetoelastic anisotropies. This can be achieved by modifying the amount of crystallized fraction via changes in the chemical composition of the nanocrystals and/or the matrix. In the case of Fe-Co, magnetic softness is attained by decreasing the Co content or with the addition of elements like Si or Al.