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Fe–Co–Nd–Dy–B glassy alloys are a current type of ferromagnetic material. To increase their glass-forming ability against the growth of a crystallization phase, the effects of the addition of transition metals TM (TM=V, Nb, Ta, Cr, Mo, and W) on the glass-formation ability and magnetic properties of Fe[sub 62]Co[sub 9.5]Nd[sub 3]Dy[sub 0.5]B[sub 25] glassy alloy have been investigated. The substitution of 2 at. % elements TM (=Nb, Ta, Mo, and W) for Fe and Co increases crystallization temperature T[sub x] and decreases the onset temperature of solidification T[sub m], leading to a significant increase in the thermal stability against crystallization for Fe[sub 60.3]Co[sub 9.2]TM[sub 2]Nd[sub 3]Dy[sub 0.5]B[sub 25]. The difference (ΔT[sub x]=T[sub x]-T[sub g]) between T[sub x] and the glass transition temperature T[sub g] increases from 55 K at 0 at. % TM to 87 K at 2 at. % TM. The bulk glassy alloy with a diameter up to 1.2 mm was produced by copper mold casting. Also no distinct changes in T[sub g], T[sub x] and ΔT[sub x] are seen for the addition of Cr and V. The results can be explained by the difference of atomic size in the additional elements. The saturation magnetization decreases slightly by the addition of 2 at. % TM elements. The saturation magnetization and coercive force of glassy Fe[sub 60.3]Co[sub 9.2]TM[sub 2]Nd[sub 3]Dy[sub 0.5]B[sub 25] alloys are 1.13 to 1.19 T and 3.85–4.98 A/m, respectively. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The superplastic deformation behavior of the ferromagnetic CoFeNbB bulk metallic glass (BMG) in the supercooled liquid region was investigated. At a given temperature, the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at high strain rates. The high thermal stability of this glassy alloy system offers an enough processing window to thermoplastic forming (TPF), and the strong processing ability was examined by simple micro-replication experiments. It is demonstrated that the TPF formability on length scales ranging down to nanometers can be achieved in the selected experimental condition. Based on the analysis of deformation behavior, the nearly full density sample (i.e. nearly 100%), was produced from water-atomized glassy powders and consolidated by the hot-pressing technique. The sample exhibits good soft-magnetic and mechanical properties, i.e., low coercive force of 0.43 Oe, high initial permeability of 4100 and high Vickers hardness 1398. These results suggest that the hot-pressing process opens up possibilities for the commercial exploitation of BMGs in engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: We developed Ni- and Be-free Zr45+x Cu40−x Al7Pd5Nb3 bulk metallic glasses with large glass-forming ability and unusual plasticity. The alloys have large critical diameters (larger than 10mm) in a wide composition range (x=0–20). The Zr50Cu35Al7Pd5Nb3 and Zr55Cu30Al7Pd5Nb3 alloys exhibit the largest critical diameter (between 18 and 20mm). The Zr45+x Cu40−x Al7Pd5Nb3 bulk metallic glasses also have large plastic elongation in wide composition range (x=10–17). The Zr62Cu23Al7Pd5Nb3 bulk metallic glass exhibits significant plasticity (over 20% of plastic elongation). With increasing Zr content, the compressive strength decreases except for the Zr67Cu18Al7Pd5Nb3 alloy. The fragility parameters were calculated to evaluate the glass-forming ability and plasticity. The fragility exhibits more sensitive correlation with plasticity than glass-forming ability. The ZrCuAlPdNb bulk metallic glasses have high crystallization activation energies of above 300kJ/mol. The ZrCuAlPdNb bulk metallic glasses are favorable for application to biomaterials. [Copyright &y& Elsevier]

Abstract: The propagation characteristics of a shear horizontally polarized SH wave, (which proceeds horizontally with respect to free surfaces in isotropic materials) passing through an annealed Zr55Cu30Ni5Al10 glassy alloy were investigated in terms of the acoustic determination of phases during annealing. The received wave patterns distinguished two phases; a nanocrystalline and an amorphous phase. The amorphous phase was composed of three kinds of structural colonies, 0.24, 0.59 and 0.72mm in size. The ordering of the amorphous phase is related to increase in wave velocity, damping ratio, phase degree and wavelength, accompanied by frequency conversion. Thus, the acoustic analysis method using diffracted SH ultrasonic waves can act a useful probe for determining the amorphous phase of glassy alloys, and is more precise than the X-ray diffraction method. [ABSTRACT FROM AUTHOR]

Abstract: Titanate nanomesh layers were fabricated on Ti-based bulk metallic glass (BMG) to induce bioactivity in the form of apatite-forming ability. Titanate nanomesh layers were prepared by hydrothermal–electrochemical treatment at 90°C for 2h, with an aqueous solution of NaOH as an electrolyte. A constant electric current of 0.5mAcm−2 was applied between the BMG substrate and a Pt electrode acting as the anode and cathode, respectively. A nanomesh layer, consisting of nanowires (∼20nm in diameter) formed on the BMG. An immersion test in simulated body fluid for 12 days revealed that the titanate nanomesh layer on the BMG promoted the growth of bone-like hydroxyapatite. [Copyright &y& Elsevier]

Abstract: The authors successfully formed a bond between bioactive hydroxyapatite (HA) ceramics and titanium (Ti)-based bulk metallic glasses (Ti40Zr10Cu36Pd14: BMG) through a growing integrated layer (GIL) to develop a new type of biomaterial. The GILs were formed on the BMG surfaces by hydrothermal–electrochemical (HE) techniques. The BMG substrates were treated in a 5mol/L NaOH solution at 90°C for 10–120min while a constant electric current of 0.5mA/cm2 was maintained between the electrodes. Then the BMG disks with the GIL and a powder mixture of CaHPO4·2H2O and Ca(OH)2 were simultaneously treated with an autoclave for hydrothermal hot-pressing (HHP) (150°C, 40MPa, 2h). Direct bonding between the HA ceramics and the BMG disks could be achieved through the above processing method. Consequently, to the best of our knowledge, this is the first demonstration of the usefulness of a series of hydrothermal techniques (HE and HHP) for direct bonding of bulk ceramics and bulk metallic materials. [Copyright &y& Elsevier]

A Zr48Cu36Al8Ag8 bulk metallic glass (BMG) containing spherical pores with 3.9% porosity was prepared by melting a Zr48Cu36Al8Ag8 powder under 1.0MPa pressurized helium. Annealing treatment of the porous alloy in a supercooled liquid region causes expansion of the pores. Highly porous BMG with a cellular structure was prepared by sudden reduction of the helium pressure in the crucible before quenching. The porous alloys exhibited significant plasticity due to a high density of shear bands initiated from pores. [Copyright &y& Elsevier]

Abstract: Foaming of a Zr-based metallic glass in the supercooled liquid is successfully performed by introducing pressurized pores and subsequent isochronal annealing. Melting of a Zr48Cu36Al8Ag8 powder under 12 MPa pressurized helium atmosphere followed by water quenching introduces spherical helium pores, whose average diameter and volume fraction are estimated respectively to be 30 μm and 7%, into a fully glassy bulk Zr48Cu36Al8Ag8 alloy. The isochronal annealing of the porous alloy below the crystallization temperature under atmospheric pressure of argon enables the expansion of pores by viscous flow deformation of the supercooled liquid, resulting in a high porosity structure up to 70% with a uniform cell size and cell distribution. [Copyright &y& Elsevier]

Fe-Cr-based metallic glasses (MGs) have attracted extensive attention for industrial applications due to corrosion resistance that is superior to that of their crystalline counterparts. In this work, the effect of Si concentration on the electrochemical corrosion and passivation behavior of Fe 43 Cr 15 Mo 14 C 10− x B 5 Ni 3 P 10 Si x ( x  = 0, 2, 4, 6 at.%) MGs in a 3.5 wt% NaCl solution has been investigated by performing potentiodynamic polarization measurements, electrochemical impedance spectroscopy, cathodic polarization, the Mott-Schottky approach, and X-ray photoelectron spectroscopy (XPS). The addition of a small amount of Si (≤4 at.%) is found to have a beneficial effect on improving the thermal stability and corrosion resistance for this Fe-Cr-based MG system. However, higher Si amounts deteriorate the thermal stability due to precipitation of a (Fe, Cr, Mo) 23 (C,B) 6 phase. Also, all electrochemical measurements show that 4 at.% Si is high enough to improve the passivity stability of the system, whereas higher amounts of Si do not significantly improve the corrosion behavior. The improved passivation ability and corrosion resistance of the Si-doped MGs can be attributed to the formation of a dense and stable passive film rich in Si- and Cr-oxides. [ABSTRACT FROM AUTHOR]

Microwires of Gd 20 Ho 20 Er 20 Al 20 TM 20 (TM = Fe, Co and Ni) high-entropy metallic glasses (HE-MGs) are successfully fabricated by a melt-extraction method, which exhibit good magnetocaloric properties. The maximum magnetic entropy change and refrigerant capacity under 5 T of the Gd 20 Ho 20 Er 20 Al 20 Co 20 HE-MG microwire can reach 10.2 J kg −1 K −1 and 625 J kg −1 , respectively. In addition, the magnetocaloric properties of the HE-MG microwires can be widely tuned by doping different transition metals. The HE-MG microwires combining high heat-exchange efficiency and excellent mechanical properties are attractive candidates for applications in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

We report a new (Fe (1 − x ) Ni x ) 78 Si 4 B 13 P 5 ( x = 0–0.8) alloys with high AFA and stability of super cooled liquid region. By tuning the ratio of Fe and Ni based on the Fe 78 Si 4 B 13 P 5 alloys, these alloys exhibit tunable and attractive performance is obtained, containing tunable B s of 0–1.57 T, low H c of 2.1–0.7 A/m, high μ e of 9–25 × 10 3 and obviously improved anti-corrosion which meets the requirement of most electric devices. These alloys with similar manufacturability are promising candidates for the application as soft-magnetic materials in electric devices and brazing materials. [ABSTRACT FROM AUTHOR]

A bicontinuous nanoporous NiCoCuY metal/metal-oxide composite was fabricated by one-step de-alloying Al 85-x Ni 6 Y 6 Co 3 Cu x (x = 1, 3 and 5) metallic glasses in alkaline solutions. The electro-chemical performance of the nanoporous composites as binder-free electrodes has been evaluated. It is found that 3 at.% Cu addition can achieve the largest capacitance which is attributed to the increase in electric conductance. The capacitance of nanoporous composites can reach as high as 1.22 F cm −2 if the Al 82 Ni 6 Y 6 Co 3 Cu 3 sample was de-alloyed in 4 M KOH for 50 min. Such a one-step strategy of de-alloying metallic glass not only generates a promising functional material for energy storage, but also provides a facile way for decreasing the resistance of electrode material. [ABSTRACT FROM AUTHOR]

The advanced efficiency of metallic glasses in degrading organic water pollutants has attracted wide interests. Yet the decolorization efficiency decreases in alkaline solutions which remains a challenge for their application. In this work, the performance of Al 91-x Ni 9 Y x (x = 0, 3, 6, 9 at.%) metallic ribbons in degrading azo dye in aqueous solutions at wide pH conditions is studied. It is surprising to find that the reaction activity of Al-based metallic glass in alkaline and acidic azo dye solution is about 1.5 and 189 times higher than that in neutral solutions, respectively. The low reaction activation energy and formation of nano-porosity on the surface of metallic glass are responsible for the high reactivity in alkaline and acidic solutions. The reaction activity can be further enhanced by modifying the alloy composition. These findings suggest that the Al-based metallic glasses hold promising potential in degrading azo dyes solutions, especially in alkaline and acidic environments. [ABSTRACT FROM AUTHOR]

Fe 38 Ni 38 Nb 2.5 B 21.5− x − y P x Si y ( x , y = 1–8) bulk metallic glassy alloys with high glass forming ability and excellent magnetic properties were developed. Bulk samples with maximum diameters of 3 mm are fabricated by copper mold casting method. The glassy alloys have large Δ T x of 40–70 K. The alloys exhibit excellent magnetic properties like extremely low H c of 0.5–0.8 A/m, high μ e of 1.6–2.85 × 10 4 and comparatively high B s of 0.6–0.8 T which changes regularly with the content variations of P, B and Si. By ascertaining applicability of the empirical GFA criterions, T rg , α , β and γ can be used in evaluating the GFA of FeNiBSiPNb system alloys. [ABSTRACT FROM AUTHOR]

Magnetic properties and magnetocaloric effect in (Fe 0.76 − x Tm x B 0.24 ) 96 Nb 4 ( x = 0, 0.01, 0.05, 0.1, 0.17 and 0.18) metallic glasses have been studied. The appropriate substitution of Fe by Tm increases the glass-forming ability of the alloys and allows tuning the Curie temperature ( T C ) to near room temperature. A linear relationship between magnetic entropy change and saturation magnetization has been observed. The formation of minority nanocrystalline Tm 2 Fe 14 B 1 phase has been observed at higher Tm additions, which could influence the magnetocaloric effect of the alloy. These Tm doped Fe-based alloys, with enhanced thermal stability, good magnetocaloric responses and tunable T C , are good candidates for near room-temperature magnetic refrigerants. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect of (Fe 0.71 RE 0.05 B 0.24 ) 96 Nb 4 (RE = Tb, Ho and Tm) bulk metallic glasses (BMGs) of diameters up to 6.5 mm were attained by 4.8 at.% RE alloying. The Curie temperature ( T C ) of Tm doped alloy, being the highest among these alloys, deviates from typical relationship between T C and de Gennes factor. Its unique electronic structure has been suggested to attribute to the observed trend. Furthermore, Tm doped alloy presents the largest peak magnetic entropy change ( | Δ S M pk | ) of 1.21 J kg −1 K −1 for an applied field of 1.5 T, which compares favorably with those of other Nanoperm-type alloys. The phenomenological universal curve for Δ S M demonstrates that alloys exhibit similar critical exponents at T C . This family of heavy RE doped Fe-based BMGs is potential candidate used as bulk magnetic refrigerants with the final required shapes. [ABSTRACT FROM AUTHOR]

In this article, we report the formation of the high-entropy Gd 20 Tb 20 Dy 20 Al 20 M 20 (M = Fe, Co and Ni) bulk metallic glasses with good magnetocaloric properties. Compared with most of the rare earth based metallic glasses, these alloys are found to have the comparably large maximum magnetic entropy changes (Δ S M ), but much broader widths of the Δ S M peaks, and hence larger refrigerant capacity ( RC ). This can be attributed to the combination of the spin glass behaviors and the complicated compositions in these alloys. Our work show that the high entropy bulk metallic glasses is a promising candidate material as the magnetic refrigerant. [ABSTRACT FROM AUTHOR]

In the present work, the cracks formation and propagation behavior of a ductile Zr-based bulk metallic glass with single dominant shear band deformation was investigated. From the ideal compressive load–displacement curve of the sample with single shear band deformation, the instant at which the shear band turns into cracks and the total area of cracked-regions prior to failure were analyzed. Further investigations revealed that the micro-cracks might have originated from the local planar faults or defects within the shear plane along the shear direction. The existence of such planar faults (steps) was consistent with the observations of the surfaces of unfractured and fractured samples. Based on these results, a new interpretation of how shear bands evolve into the present micro-cracks was proposed. These novel results provide a new perspective to understand the deformation behavior of metallic glasses. [ABSTRACT FROM AUTHOR]

A novel in situ forming Mg66Zn29Ca4Y1 composite comprising microsized icosahedral quasicrystal phase (I-phase) particles dispersed within a Mg-based metallic glass matrix was synthesized. The size and volume fraction of the I-phase particles are ∼25–35μm and ∼10%, respectively. The I-phase particles can noticeably improve both the strength and plasticity of the composite. The mechanism of the hard I-phase particles on the deformation and fracture behaviors of the composite and the synthesis strategy of the composite are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] A mass of amorphous carbon nanotubes have been synthesized. [•] The Fe76Si9B10P5 particles were employed as both the catalyst and support. [•] C2H2 and Ar were employed as carbon precursor and carrier gas, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The present study estimates the feasibility of ultrasonic bonding technique to bond Zr55Cu30Ni5Al10 metallic glass to each other. Bonding without external heat has been challenged, as well as that with assisting external heat. The results indicate that the metallic glass foils can be bonded even under the condition without external heat. Although the strength of the bonds is low due to the insufficient fraction of adhered area, the bonds are successfully formed retaining the glassy structure. The adhered area can be increased by employing the bonding condition with an external heat up to 423K, which is still lower than the glass transition temperature of the Zr55Cu30Ni5Al10 metallic glass alloy. [Copyright &y& Elsevier]