Analysis of crystallization process of selected Fe-based bulk metallic glasses

Purpose: The paper mainly aims to present the influence of annealing temperature on structural changes and magnetic properties of selected Fe-based bulk metallic glasses with chemical composition of Fe43Co14Ni14B20Si5Nb4 (at.%). Design/methodology/approach: The investigated samples were cast in form of the rods with diameter of 1.5 mm by the pressure die casting method. The structure changes in function of annealing temperature were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. The crystallization behaviour of the studied alloy was also examined by differential scanning calorimetry (DSC). Magnetic measurements of annealed samples included the initial magnetic permeability and the magnetic permeability relaxation measurements. Findings: The annealing process at temperature range from 373 to 773 K caused a structural relaxation of tested material, which caused the atomic rearrangements and changes of physical properties in relation to as-cast state. The annealing at higher temperatures (823-923 K) obviously caused a formation of a-Fe and iron borides crystalline phases. The increasing of annealing temperature significantly improved soft magnetic properties of examined alloy by increase the initial magnetic permeability and decrease the magnetic permeability relaxation. Practical implications: The investigation of the crystallization process of Fe-based metallic glasses is important for understanding the mechanisms of forming controlled microstructures of these materials with specific physical properties. Originality/value: A proper understanding of crystallization process of Fe-based bulk metallic glasses is still novel scientific problem.