Continuous casting of thick Fe-base glassy plates by twin-roller melt-spinning

A glassy Fe-base alloy plate with a composition of Fe36Co36B20Si4Nb4 (at.%) was prepared by a twin-roller continuous casting method. The alloy plate had a width of 70 mm, a thickness of 0.5 mm and a length of 150 mm. The cast plate contained small crystalline grains in the glassy matrix. These crystalline grains were identified as an α-Fe (cI2) phase. Thermal characteristics of the plate are almost consistent with those of the melt-spun ribbon, while the exothermic heat of crystallization for the cast plate is about 5% smaller than that for the ribbon. The coercive force (Hc) and maximum permeability (μm) of the Fe-base alloy in a ring form of 10 mm in outer diameter, 5 mm in inner diameter and 0.6 mm in thickness made by mechanical machining from the cast plate are 2.1 A/m and 40,000, respectively, for the as-cast one, and 1.6 A/m and 170,000, respectively, for the annealed one at 723 K for 1800 s under rotation magnetic field of 80 kA/m. It can be thus said that the cast plate has good soft magnetic properties. The possibility of forming a glassy alloy plate by twin-roller continuous casting is confirmed and the Fe-base glassy alloy plate produced by the developed continuous process will be applicable for magnetic parts.