Structure, thermal and magnetic properties of (Fe72B20Si4Nb4)100-xYx(x=0.3) metallic glasses

Purpose The work presents structure characterization, thermal and soft magnetic properties analysis of selected Fe-based metallic glasses in as-cast state and after crystallization process. Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 and Fe70B19Si4Nb4Y3 metallic glasses in form of ribbon. The amorphous structure of tested samples was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. The crystallization behaviour of the studied alloys was examined by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The soft magnetic properties examination of tested materials contained initial magnetic permeability and magnetic permeability relaxation measurements. Findings: The XRD and TEM investigations confirmed that the studied alloys Fe72B20Si4Nb4 and Fe70B19Si4Nb4Y3 were amorphous in as-cast state. The liquidus temperature assumed as the end temperature of the melting isotherm on the DTA reached a value of 1550 K and 1560 K for Fe72B20Si4Nb4 and Fe70B19Si4Nb4Y3 alloy, adequately. The analysis of crystallization process indicated that onset and peak crystallization temperature increased with increasing of heating rate at DSC measurements. The samples of Fe72B20Si4Nb4 alloy presented two stage crystallization process. The initial magnetic permeability of examined samples increased together with the increase of annealing temperature and reached a distinct maximum at 773 K for Fe72B20Si4Nb4 and at 723 K for Fe70B19Si4Nb4Y3 alloy. Practical implications The increasing of annealing temperature significantly improved soft magnetic properties of examined alloys by increase the initial magnetic permeability. Originality/value: The applied investigation methods are suitable to determine the changes of structure and selected properties between studied alloys, especially in aspect of the soft magnetic properties improvement after annealing process.