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The glass-forming ability of Fe-based bulk metallic glasses is strongly correlated with the amount of metalloids they contain. Starting from a ferromagnetic and ductile Fe-based metallic glass of composition (Fe0.582Co0.418)80Cr10Zr10, we were able to produce several bulk metallic glasses by alloying titanium and boron. The resulting alloys of composition [(Fe0.582Co0.418)0.81Cr0.10Zr0.07Ti0.02]100-xBx (x=10–20 at. %) exhibit a critical casting thickness of 0.5 mm, a wide undercooled liquid region ΔTx(=Tx-Tg) of 16–84 K, and ferromagnetic properties. dc magnetization measurements show an inverted hysteresis at room temperature, and small-angle neutron scattering on the [(Fe0.582Co0.418)0.81Cr0.10Zr0.07Ti0.02]90B10 bulk metallic glass reveals a power-law dependence of the differential scattering cross-section. The latter indicates a pronounced short-range order with a surface fractal dimension of 2.5. A splat-cooled sample of the same composition does not reveal this pronounced short-range order, but still an inverted hysteresis. From the scaling behavior of the magnetization curves, measured at different temperatures between 50 and 300 K for the splat-cooled sample, we find that an antagonistic internal magnetic field is present in this material. The resulting inverted hysteresis is presumably caused by interacting superparamagnetic and blocked regions. [ABSTRACT FROM AUTHOR]

The glass-forming ability of Fe-based metallic glasses has a direct relationship with their metalloid content. A good glass-former usually needs a metalloid content of approximately 20 at. %. However, a high metalloid content causes deterioration not only in magnetic properties but also in elasticity and plasticity. Based on destabilization of the solid state we have developed a series of metalloid-free Fe-based metallic glasses of composition (Fe0.582Co0.418)100-x-yCrxZry (10<=x<=28 and 8<=y<=11). Via this destabilization the liquid state is stabilized, which results in a decreasing liquidus temperature. The mechanical and magnetic properties of the metalloid-free Fe-based metallic glass with the highest Fe and Co fractions were analyzed. The alloy of composition (Fe0.582Co0.418)80Cr10Zr10 exhibits bending elasticity and plasticity. Magnetization measurements reveal a saturation magnetization of up to 1.1 T and an inverted hysteresis. The origin of this inverted hysteresis presumably lies in the inclination to decompose in a ferromagnetic iron-rich α1 phase and an antiferromagnetic chromium-rich α2 phase. [ABSTRACT FROM AUTHOR]