Effect Of The External Field On The Soft Magnetic Properties And Microstructure Of Directly Cast Fe75p8.7b5c7si4.3 Nanocrystalline Sheets

A new method to fabricate soft magnetic bulk metallic glasses (BMGs) by an injection casting with applying external magnetic field during solidification has been developed. The effect of applying magnetic fields (H-a) on soft magnetic properties and microstructure of Fe75P8.7B5C7Si4.3 alloy sheets with dimension of t x 4mm x 15mm (t = 1-3 mm) have been studied. The microstructure shows that the fully amorphous is attained by the applying magnetic field even at the core region of the thicker sheets with t = 3mm. All studied sheets exhibit similar saturation magnetization of 1.23-1.25 T, but the coercivity and resistivity are strongly dependent on the thickness t and the strength of magnetic field H-a, where H-c increases with t, the slope of H-c versus t decreases with the increase of H-a, and the resistivity increases with the increase of H-a. The changes of coercivity and resistivity are strongly related to the fully amorphous induced by H-a. The external magnetic field has significant improvement in glass forming ability, and thus coercivity and resistivity for the studied sheet, especially for larger t = 3 mm. This study suggests that applying a magnetic field during the casting process provides a useful way to produce high-performance magnetically soft Fe-based BMGs. (C) 2015 AIP Publishing LLC.