Effect Cu and La on the Solidification Structure and Magnetic Properties of Fe-6.5wt.%Si Alloy under Arc Melting

This study investigates the influence of Cu and La additions on the solidification structure and phase formation behavior of Fe-6.5wt%Si high silicon steel. The alloy's phase composition and structure were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic performance was measured using a high and low-temperature vibration magnetometer. The results revealed that the microstructure of the Fe-6.5wt.%Si alloy ingot, treated with Cu and La inhibitors, is segmented into three layers. From the bottom to the top, the phase morphology is fine crystals, columnar crystals, and isoaxial crystals. Adding Cu and La inhibitors significantly refined the Fe-6.5wt.%Si alloy; adding 0.05% Cu transformed thick columnar crystals into slender branches, while 0.03% La led to a uniform refinement of grains. Cu addition maintained the alloy saturation magnetization strength but increased coercivity. La addition decreased the alloy's saturation magnetization and increased coercivity.