Based on the consideration of both the resistance of amorphous phase against crystallization and the stability of under-cooled liquid against competing crystalline phase formation, a criterion ω, defined as Tg/Tx − 2Tg/(Tg + Tl) (Tg, Tx and Tl denote the glass transition temperature, the onset crystallization temperature and the liquidus temperature, respectively), has been proposed for evaluating the glass-forming ability (GFA) of bulk metallic glasses (BMGs). A survey of the readily available experimental data associated with the thermal analysis of various glass-forming alloys shows that the new criterion ω exhibits the best correlation with the maximum section thickness (Dmax) as well as the critical cooling rate (Rc) for glass formation among other criteria proposed in recent years, such as Trg(=Tg/Tl), ΔTx(=Tx − Tg), γ(=Tx/(Tg + Tl)), γm(=(2Tx − Tg)/Tl), ΔTrg(=(Tx − Tg)/(Tl − Tg)), δ(=Tx/(Tl − Tg), φ(=Trg(ΔTx/Tg)0.143, α(=Tx/Tl), β(=(Tx/Tg + Tg/Tl) and β(=Tx × Tg/(Tl − Tx)2). Therefore, it can be anticipated that this new criterion will be used as a useful and efficient guideline for exploring new BMG formers.

The effects of partial substitution of Y for Fe on the glass-forming ability (GFA), mechanical, thermal and magnetic properties of quinary Fe73−xNb4Hf3YxB20 (x = 0–3 at.%) alloys were investigated. The replacement of 1–3 at.% Fe by Y increased thermal stability of the supercooled liquid in the Fe–Nb–Hf–Y–B alloys, enabling the fabrication of bulk metallic glasses (BMGs) with diameters up to 4 mm from the original 2 mm. Properties of Fe73−xNb4Hf3YxB20 BMGs were measured, yielding a rather high saturation magnetization of 1.05–1.22 T, low coercive force of 1.6–3.6 A/m, high compressive fracture strength of 3200–3490 MPa, Yong's modulus (E) of 177–190 GPa and compressive strain before failure ∼2%. Furthermore, the role of Y addition on the GFA as well as mechanical and magnetic properties is also discussed.

The influence of Cr addition on glass-forming ability (GFA), corrosion resistance, and magnetic and mechanical properties of the Fe–Co–B–Si–Nb bulk glassy alloy (BGA) has been investigated. Except for a slight decrease in its GFA, the Cr addition caused an increase of corrosion resistance as well as an improvement of soft-magnetic properties and mechanical behaviors for this alloy within the composition range studied. BGA rods with diameters up to 4 mm were produced by copper mold casting technique. These glassy alloys exhibit a rather high saturation magnetization of 0.811–1.040 T, low coercive force of 0.6–1.7 A/m, high effective permeability of (2.37–3.41) × 104 at 1 kHz under a field of 1 A/m, and extremely low saturation magnetostriction of (0.43–4.17) × 10−6. These BGAs also possess ultrahigh fracture strength of 4010–4274 MPa, Young's modulus of 200–215 GPa, elastic strain of about 2% and plastic strain reaching 0.7%. Moreover, the corrosion rate and corrosion current density of the glassy alloy rods in simulated industrial environments contaminated with SO2 decreased significantly from 3.47 × 10−2 to 9.2 × 10−3 mm/year and 1.5 × 10−5 to 6.7 × 10−7 A/cm2, respectively, with increasing Cr content from 0 to 4 at.%, illustrating that the addition of Cr is effective in increasing the corrosion resistance. Furthermore, the mechanisms for the high GFA, distinct plasticity strain, good corrosion resistance, and excellent soft-magnetic properties of the Fe-based BGAs are discussed.

Fe-based ferromagnetic [(Fe1−xNix)0.75B0.2Si0.05]96Nb4 (x = 0, 0.2 and 0.4) bulk glassy alloys (BGAs) with a diameter of 2 mm were prepared by copper mold casting. The corrosion behavior of glassy alloy rods obtained was investigated in 0.5 M NaCl, 0.5 M NaOH and 0.5 M H2SO4 aqueous electrolytes, respectively, using weight loss and electrochemical polarization measurements. It was found that the corrosion rates significantly decrease with an increase in Ni content in all examined solutions. The Ni-containing BGAs are spontaneously passivated with wide passive regions and low passive current densities in NaCl and NaOH solutions, but exhibit the active–passive–transpassive behavior in H2SO4 solution. The partial substitution of Ni for Fe results in a considerable improvement on the corrosion resistance of [(Fe1−xNix)0.75B0.2Si0.05]96Nb4 BGAs, because of the structural and chemical homogeneousness of the amorphous phase and the effect of Ni on promoting the formation of a passive film. Besides their high glass-forming ability (GFA), excellent soft-magnetic properties and good mechanical performance, which have been reported before, these FeNi-based BGAs also feature rather high corrosion resistance.

Effects of the Cr addition on glass formation, magnetic and corrosion properties of {[(Fe0.6Co0.4)0.75B0.2Si0.05]0.96Nb0.04}100−xCrx (x = 1, 2, 3, 4 at.%) alloys have been investigated. It was found that the addition of Cr element slightly decreases the glass-forming ability (GFA), but is very effective in increasing corrosion resistance and improving soft magnetic properties for this Fe–Co–B–Si–Nb bulk glassy alloy within the composition range examined. The Fe–Co–B–Si–Nb–Cr alloys exhibit high GFA. Full glassy rods with diameters up to 4 mm can be synthesized by copper mold casting. The Fe-based bulk glassy alloys (BGAs) exhibit a high saturation magnetization of 0.81–0.98 T as well as excellent soft magnetic properties, i.e., extremely low coercive force of 0.6–1.6 A/m and super-high initial permeability of 26,400–34,100. Furthermore, corrosion measurements show that corrosion rate and corrosion current density of these Fe-based BGAs in 0.5 M NaCl solution decrease from 7.0 × 10−1 to 1.6 × 10−3 mm/year and 3.9 × 10−6 to 8.7 × 10−7 A/cm2, respectively, with increasing Cr content from 0 to 4 at.%. The success of synthesizing the new Fe-based BGAs exhibiting simultaneously high GFA as well as excellent good soft magnetic properties combined with high saturation magnetization and enhanced corrosion resistance allows us to expect future progress as a new type of soft magnetic materials.