Stability of a micro molten pool for fabricating glass-coated Fe-based alloy microwires

To keep micro molten pools stable is a premise for fabricating glass-coated metal microwires continuously by the glass-coated melt spinning method. Theoretic calculation was used to analyze the effects of the structural parameters of an induction heater, heating current, pool volume (mass) and position in the induction heater on the temperature and levitation force of the Fe-based alloy micro molten pool. The levitation force of the micro molten pool, as the temperature is 1280℃, increases with the increase in cone angle and bottom hole height of the induction heater, as well as the decrease of the induction heater's height, bottom hole radius and distance from the molten pool center to the upper surface of the bottom hole, and reducing the heating current and the pool volume (mass) is beneficial to the decrease of the difference between gravity and levitation force. The appropriate structural sizes of the integral induction heater for preparing glass-coated Fe-based alloy microwires are the cone angle of the induction heater 120 to 130°, height of the induction heater 12 to 14 mm, bottom hole height 2 to 4 mm, and bottom hole radius 3 to 4 mm. The reasonable distance from the molten pool center to the upper surface of the bottom hole is 4 to 6 mm and the suitable mass of the Fe-based alloy micro molten pool is 1.5 to 2.0 g. Using the optimized integral induction heater and keeping the volume (mass) of the Fe-based alloy micro molten pool almost invariant by feeding continuously, glass-coated Fe-based alloy microwires are fabricated continuously and stably.