Thermal, magnetic and mechanical behavior of large-sized Fe-based amorphous alloy ribbons by twin-roll strip casting

Fe-based amorphous alloys are characteristic of high saturation magnetization, low coercivity, and low core loss, which holds a grand promise for several engineering applications, such as soft magnetic, corrosion-resistant and wear-resistant coatings. However, poor amorphous forming ability (AFA) and size limit remain the main obstacles in applications. This study aims to address those scientific-technical challenges through a twin-roll strip casting method to yield two cost-effective Fe-based amorphous alloy (Fe73Mo4B5Si5P8C5 and Fe80Al2B5P9C4) ribbons with ca. 200-μm thickness and promising soft magnetic functions. Their crystallization behavior, thermal stability, magnetic properties, and mechanical performance for melt-spun and annealed alloys were studied systematically. Results demonstrate that Fe73Mo4B5Si5P8C5 and Fe80Al2B5P9C4 present good thermal stability, a large temperature interval between Tg and Tx1(61.7 °C for Fe73Mo4B5Si5P8C5 and 43.1 °C for Fe80Al2B5P9C4) infers that both the alloys have good processability. Meanwhile, Fe80Al2B5P9C4 amorphous alloy subjected to annealing at 450 °C for 300 s exhibited high saturation magnetization greater than 1.5 T, low coercivity of 5.3 A/m and high hardness of 989 Hv, which were attributed to the utterly amorphous structure and superior thermal stability achieved by twin-roll strip casting. Integrating the favorable mechanical, magnetic characteristics and high manufacturability of ultra-thick Fe73Mo4B5Si5P8C5 and Fe80Al2B5P9C4 amorphous alloys indicates that twin-roll strip casting is a sound solution to tackle the poor AFA and size limit in production of amorphous ribbons.