Nanocrystalline, magnetically soft (Fe-Co)-(Hf,Zr,Nb)-Cu-B alloys for application at elevated temperature

Aim of project

For several years lots of studies concerning nanocrystalline magnetically soft materials have been carried out. Special interest is given to materials obtained by partial crystallization of metallic glasses, with better magnetic properties than those found for their amorphous counterparts. In order to increase the Curie temperature of the amorphous matrix, iron is partially replaced with cobalt, those alloys are called HITPERM. Magnetically soft nanomaterials for high-temperature applications have to fulfi ll two basic requirements: (i) very soft magnetic behavior at elevated temperatures, and (ii) stable performance at elevated temperatures for the time of application.

As the studied materials, (Fe1-zCoz)93-x(Hf1-vZrv)xCu1B6 (x=7 and 9, v=0, 0.5, z=0 — 1) were selected. The as-quenched alloys were isothermally nanocrystallised at 500–650°C for 1 h, and exposed to long-term annealing at 500–600°C for up to 3000 h. Structure of the alloys was studied with X-ray diff raction. The quasistatic hysteresis loops of 10 cm long strips were measured at temperature from 20 to 650°C, with the maximum magnetic fi eld of 4.8 kA/m.

Expected results
The aims of the project are to propose the chemical composition and thermal conditions of nanocrystallization for nanocrystalline soft magnetic materials. The materials should have better magnetic properties at room and elevated temperatures than the already used materials.