Synthesis of ferromagnetic Fe-based bulk glassy alloys in the Fe–Si–B–P–C system

Abstract

Multi-component Fe76P5(BxSiyCz)19 glassy alloys were fount to exhibit a distinct glass transition, followed by a supercooled liquid region before crystallization in a rather wide composition range. The largest value of the supercooled liquid region defined by the difference between the glass transition temperature (Tg) and crystallization temperature (Tx), ΔTx (=Tx − Tg) was 54 K for Fe76P5(Si0.3B0.5C0.2)19. Furthermore, the crystallization of the glassy alloy occurs through a single exothermic reaction, which means simultaneous precipitation of several kinds of crystallites leading to higher glassy forming ability (GFA) due to the necessity of the atomic rearrangement on a long range scale. By copper mold casting, bulk glassy alloy rods with diameters up to 3 mm were produced. The representative Fe76P5(B0.5Si0.3C0.2)19 alloy exhibits rather high saturation magnetization of 1.44 T with good soft-magnetic properties, i.e., low coercive force of 1.2 A/m, and high effective permeability of 17,600 at 1 kHz under a field of 1 A/m. The bulk glassy alloy also possesses superhigh fracture strength of 3700 MPa and Young's modulus of 185 GPa. This new ferromagnetic bulk glassy alloy simultaneously exhibiting high GFA, rather high saturation magnetization, excellent soft-magnetic properties and superhigh fracture strength is promising for future applications as not only functional but also structural material.