Fe-based Metallic Glass Research Articles

Bio-corrosion studies of Fe-based metallic glasses

Abstract Fe-based metallic glasses are known for their high corrosion resistance. Also, the corrosion resistance of metallic glasses are greatly influenced by the alloying elements. In the present study, the bio-corrosion resistance of two Fe-based metallic glasses (Fe32Ni36Cr14P12B6 and Fe67Co18B14Si1) has been studied. The bio-compatibility of these metallic glasses are studied in four simulated body fluids (SBFs), namely artificial saliva solution (ASS), phosphate-buffered saline solution (PBS), artificial blood plasma solution (ABP), and Hank’s balanced saline solution (HBSS). Potentiodynamic polarization studies are performed on both the metallic glasses, for understanding their bio-compatibility.

Surface-governed electrochemical hydrogenation in FeNi-based metallic glass

The hydrogenation and oxide formation behavior of Fe–Ni-based metallic glasses (MGs), where measurements by the conventional gas-solid reaction method are difficult, is analyzed by a two-step approach: chronoamperometry followed by cyclic voltammetry (CA + CV). We introduce a concept of effective volume by measuring the thickness of the region where the hydrogen and hydroxyl ion interactions with Fe-based MG take place, which is characterized by high-angle annular dark-field scanning transmission electron microscopy. A very constant film thickness influenced by the OH− and H+ is confirmed by TEM, where the chemical homogeneity is maintained within this region. The weight percent of hydrogen and the corresponding hydrogen-to-metal ratio are determined as 1.16% and 0.56, respectively. When compared to previous studies conducted by the electrochemical-permeation method, the H/M ratio is found to be an order of magnitude larger. Electrochemical impedance spectroscopy (EIS) and subsequent equivalent circuit modeling (ECM) of the tested ribbons resolve the surface-diffusion processes for hydride formation and oxidation kinetics. This contribution provides a different perspective for the design and study of low-cost and high-performance amorphous nanofilms for hydrogen-energy applications, particularly when the common gas-adsorption methods are problematic.

Microstructure change in Fe-based metallic glass and nanocrystalline alloy induced by liquid nitrogen treatment

The effects of acyclic liquid nitrogen (LN) treatment in a temperature range of −196 °C to 50 °C on the thermal and magnetic stability of Fe78Si9B13 and Fe73.5Si13.5B9Nb3Cu1 glassy ribbons have been studied. The intrinsic heterogeneities of the metallic glasses can be activated through cryogenic thermal cycling, making irreversible structural changes after the treatment and inducing rejuvenation to the materials. The microstructural changes of both Fe-based metallic glass (MG) and nanocrystalline alloy induced by LN treatment were investigated. The experimental results show that the LN treatment could effectively rejuvenate the Fe-Si-B MGs and change their thermomechanical and magnetic properties. Based on the partially-crystallinity and well-known magnetic constants, the increase of the energy at the order of 10 mJ/g and magnetic domain wall movement and rotation at the order of 5−6 μm and 0.5°-0.8° are found for FINEMET-type amorphous alloy after LN treatment. It is also found that LN treatment can contribute a little stored energy to the magnetic domain wall movement and magnetic domain rotation.

Fabrication, microstructure and wear properties of novel Fe-Mo-Cr-C-B metallic glass coating layers manufactured by various thermal spray processes

The metallic glass powder of newly designed Fe46.8-Mo30.6-Cr16.6-C4.3-B1.7 composition was employed to fabricate Fe-based metallic glass coating layers using representative thermal spray processes, viz. atmospheric plasma (plasma), HVOF and vacuum plasma spray (VPS). The microstructure and wear properties of the thermal sprayed Fe based metallic glass coating layers were investigated. XRD analysis results showed that all the three coating layers had broad halo peaks. Alloying element depletion was observed in the coating layer in the vicinity of the oxides. However, the VPS coating layer showed no depletion area. Wear test results showed that the VPS coating layers had the best wear resistance among all the three coating layers, whereas the plasma material had the poorest wear resistance property. Worn surface and cross-section observation revealed that the plasma material had particle boundary delamination because of its lower bonding force between the particles. Directly below the worn-out surface of the HVOF coating layers, microcracks were generated along the particle boundaries. By contrast, no defects were found at all directly under the worn-out surface of the VPS materials. The wear behavior of Fe based metallic glass coating layers fabricated in diverse thermal spray processes was discussed with respect to the microstructure.

Effect of Cooling Rate on Glass Forming Ability of Novel Fe-Based Bulk Metallic Glass

Effect of Cooling Rate on Glass Forming Ability of Novel Fe-Based Bulk Metallic Glass

Tailoring surface morphology of heterostructured iron-based Fenton catalyst for highly improved catalytic activity

Due to the great limitation of glass forming ability, precisely controlling the chemical compositions of metallic glasses (MGs) still dramatically inhibits their widespread applications in wastewater remediation. Here, heterostructured catalysts were exploited by rapid annealing of Fe-based MGs and subsequent ball milling (BM) as advanced alternatives for amorphous counterparts in Fenton-like process. It was found that the surface characteristics tailored by ball milling enable more chemically active sites due to its enlarged specific surface area, surface defects and nanosized amorphous oxide layer that significantly enhance surface-catalyzed reaction in Fenton-like process. On the other hand, high-temperature annealing induced grain growth and electrochemical potential difference induced effect of galvanic cells in multiple crystalline phases (e.g. α-Fe (Si), Fe2B and Fe3Si) further provide an important contribution to high efficiency of electron transfer in heterostructured catalysts. Since the multiphase heterostructure is easily formed by a high-temperature annealing of MGs/amorphous-crystalline composite alloys, this work aims to provide an advanced alternative of MG catalyst without the elemental limitation of glass forming ability for wastewater remediation.

Interfacial characteristics and mechanical asymmetry in Al2024 matrix composites containing Fe-based metallic glass particles

Controversy regarding the possible effects of interfacial reaction between matrix and reinforcement has recently aroused in the field of aluminum matrix composites reinforced with metallic particles. In this study, Al2024 matrix composites containing Fe-based glass particles were heat treated to investigate the interfacial microstructure and the resulting effects on the mechanical behavior. The results reveal that a submicron sized Al7Cu2Fe intermetallic phase is formed at the particle-matrix interface during solid solution treatment and the thickness of intermetallic layer increases with increasing temperature and holding time. The formation of the intermetallic phase reduces the amount of Cu available for the precipitation hardening of the matrix, consequently decreasing the strength of the composites. Furthermore, the formation of the intermetallic layer weakens the particle-matrix interface bonding strength, resulting in failure of the composites by particle debonding, which significantly deteriorated the tensile properties. Tension-compression (T/C) asymmetry of the composites is caused by the difference in damage evolution as a response to compressive or tensile loads. The composites containing large glass particles showed aggravated T/C asymmetry, and the asymmetry increased with the advancing of the interfacial reaction. Our work indicates that the formation of intermetallic compounds larger than submicron size at the interface is detrimental to the mechanical properties of aluminum matrix composites reinforced with metallic particles.

Fe-based metallic glass particles reinforced Al-7075 matrix composites prepared by spark plasma sintering

Metallic glass (MG) reinforced aluminum matrix composites (AMCs) have attracted the interest of many researchers in the past few years. In this study, Fe50Cr25Mo9B13C3 metallic glass (FMG) particles reinforced 7075 aluminum matrix (Al-7075) composites were prepared by spark plasma sintering (SPS) technique. The microstructure of the composites showed good interface bonding between the FMG particles and the matrix. The micro-hardness of the composite with 30 vol% FMG particles reached 160.63 HV, which was increased by 30% compared with that of Al-7075 (119.3 HV). The ultimate compression strength (UCS) of the composite was also improved significantly from 596 MPa for Al-7075 matrix to 749 MPa for the composite reinforced with 30 vol% FMG particles, and the compression strain of the composite reached 22%. These results indicate that the mechanical properties of the composites can be enhanced by adding high volume fraction FMG particles. The enhancement of the strength is resulted from multiple strengthening mechanisms, and the main contributions come from the thermal mismatch and grain refinement.

Correlation between deformation behavior and atomic-scale heterogeneity in Fe-based bulk metallic glasses

The correlation betweent deformation behavior and atomic-scale heterogeneity of bulk metallic glasses (BMGs) is critical to understand the BMGs’ deformation mechanism. In this work, three typical [(Fe0.5Co0.5)0.75B0.2Si0.05]96Nb4, Fe39Ni39B14.2Si2.75P2.75Nb2.3, and Fe50Ni30P13C7 BMGs exhibiting different plasticity were selected, and the correlation between deformation behavior and atomic-scale heterogeneity of Fe-based BMGs was studied. It is found that the serrated flow dynamics of Fe-based BMGs transform from chaotic state to self-organized critical state with increasing plasticity. This transformation is attributed to the increasing atomic-scale heterogeneity caused by the increasing free volume and short-to-medium range order, which facilitates a higher frequency of interaction and multiplication of shear bands, thereby results in a brittle to ductile transition in Fe-based BMGs. This work provides new evidence on heterogeneity in plastic Fe-based BMGs from the aspects of atomic-scale structure, and provides new insight into the plastic deformation of Fe-based BMGs.

Efficient nanostructured heterogeneous catalysts by electrochemical etching of partially crystallized Fe-based metallic glass ribbons

Although an increasing interest has been attracted to further develop heterostructured catalysts from metallic glasses (MGs) by heat treatment, overcoming surface oxidation effect is still a critical problem for such environmental catalysts. Herein, a short-time electrochemical etching of partially crystallized Fe-based ribbons in 0.3 M H3PO4 electrolyte enables the formation of honeycomb-like nanoporous structure as effective catalytic active sites in Fenton-like process. Studies of structure and surface morphologies reveal that the formation of nanoporous structure by potentiostatic etching originates from electrochemical potential difference of nanocrystals (α-Fe (Si) and Fe2B) and residual amorphous phase in partially crystallized ribbons, where Fe2B having a lower open circuit potential tends to be selectively dissolved. Simultaneously, thin oxide layer after electrochemical etching exposes more active sites for H2O2 activation and provides an effective protection of nanocrystals from massive loss during etching. Investigation of optimal processing conditions suggests that the selection of electrolyte plays an important role; dye degradation rates of etched ribbons in HNO3 and Na2SO4 electrolytes can also achieve at least 2 times higher than that of as-annealed ribbons. This work holds the promise to develop novel environmental catalysts by effective electrochemical etching of partially crystallized ribbons.

Laser-induced regular nanostructure chains within microgrooves of Fe-based metallic glass

Femtosecond laser-induced surface structures have been extensively investigated over decades, however, their formation is not well controlled especially for the practical use in the photonic field. We here report the highly regular nanostructure formation within the grooves of the Fe-based metallic glass, upon irradiation of two temporally delayed femtosecond laser beams. For the case of micrometer-sized groove, multiple chains of spindle-like nanostructures are developed, with the spatial periods of 667 nm and 180 nm for the chain and spindle distributions, respectively. Their arrangement properties can be modulated by varying laser parameters. On the other hand, for the case of submicrometer-sized groove, there is only one chain of spindle-like nanostructures formed inside with the improved regular appearance. Two physical effects, including the plasmonic field generation from the groove edges and the surface magnon polariton excitation within the groove, are considered responsible for the phenomena, which consequently result in the spatial interlocking of two types of ripples. The theoretical analyses match well the experimental observations.

Fabrication of homogenous subwavelength grating structures on metallic glass using double-pulsed femtosecond lasers

We report a formation of highly homogenous subwavelength grating structures on the bulk Fe-based metallic glass, using two nondegenerate linear polarization of femtosecond laser pulse sequences at certain temporal delays. In contrast to the previous observations, the well-defined surface structures can take place across the entire laser ablation regions, with the spatial period and the modulation depth of 722 nm and 115 nm, respectively. Through the Fourier transformation analysis, we introduce two parameters to quantitatively evaluate the structure uniformity. The underlying mechanisms are attributed to the surface scattered wave of the second femtosecond laser pulse onto the transient material surface tailored by the first laser pulse. Moreover, different diffusion coefficients of the chemical elements are found responsible for their various removal percentages after laser irradiation.

Co50Gd48-xFe2Nix amorphous alloys with high adiabatic temperature rise near the hot end of a domestic magnetic refrigerator

In the present work, the Curie temperature (Tc) of the Co50Gd48Fe2 amorphous alloy, which exhibits high adiabatic temperature change (ΔTad) at room temperature, was further improved by small amount of Ni substitution for Gd. The maximum magnetic entropy change (−ΔSmpeak) of the Co50Gd48-xFe2Nix (x = 1 and 2) amorphous ribbons decreases with Ni addition, but is still large than those of the Fe-based metallic glasses. The maximum ΔTad of the Co50Gd48-xFe2Nix glassy alloys near the hot end of a residential refrigerator, which is at least 65% higher than those of the Fe-based glassy ribbons, indicates that the Co50Gd48-xFe2Nix amorphous alloys are the better candidates for the domestic magnetic refrigerants.

Dry wear behavior and mechanism of a Fe-based bulk metallic glass: description by Hertzian contact calculation and finite-element method simulation

In this study, the dry-sliding characteristics of a FeCoCrMoCBY bulk metallic glass (BMG) were investigated. The results were compared with those of the conventional CoCrMo alloy and 316L stainless steel (SS). It was found that the Fe-based BMG exhibited the highest wear resistance among three investigated alloys. The wear mechanism of those alloys is the combination of abrasion and oxidation. In addition, the tribological behaviors of the Fe-based BMG were highly dependent on couple materials. The BMG/Si3N4 friction couple demonstrated a greater wear resistance than that of the BMG/Al2O3 and BMG/ZrO2. The wear resistance of these metallic materials could be correlated with their hardness and Young's modulus in terms of various wear-rate equations. Moreover, the contact mechanism of friction couples was described by Hertzian contact calculation and finite-element method (FEM) simulation to illustrate the mechanism of the good wear performance of the Fe-based BMG.

Excellent degradation performance of the Fe78Si11B9P2 metallic glass in azo dye treatment

Fe78Si11B9P2 metallic glass (MG) ribbons are proved to exhibit excellent comprehensive ability in azo dye treatment. The Fe78Si11B9P2 MG ribbons can degrade the azo dye effectively, which derived from high mass and electron transfer ability due to the cotton-like structure formed during the reaction. The degradation efficiency and reaction rate raise with the decrease of the initial Orange Ⅱ concentration, the increase of ribbon dosage and the proper addition of H2O2. The Fe78Si11B9P2 MG ribbons are more applicable in acidic and neutral solutions. Compared to the other reported Fe-based metallic glasses for dye degradation, the Fe78Si11B9P2 MG has a lower reaction activation energy and relatively good reusability in treating with azo dye. In addition, the achieved high COD removal indicates that the complex organic structures in azo dye can be decomposed completely by Fe78Si11B9P2 MG ribbons. This work not only provides a new effective and low-cost materials for wastewater treatment, but also promotes the practical applications of Fe-based MGs as functional materials.

Corrosive wear behaviors and mechanisms of a biocompatible Fe-based bulk metallic glass

Wear behaviors of the FeCoCrMoCBY bulk metallic glass (BMG), 316 L stainless steel (SS), and CoCrMo alloy under wet sliding in the phosphate buffered saline (PBS) solution were studied and compared with those under dry sliding. The Fe-based BMG exhibited an excellent corrosive wear resistance with a low wear rate of 1.84 × 10−8 mm3 mm−1•N − 1. On the contrary, the CoCrMo alloy and 316 L SS suffered from the synergistic effect of corrosion and wear in the PBS solution. The electrochemical results revealed that the Fe-based BMG possessed the greatest corrosion performance in the PBS solution among three alloys. The excellent corrosion behavior of the Fe-based BMG was attributed to the highly-protective surface passivation film enriched in Cr and Mo elements. The triobocorrosion results manifested that the great anti-corrosive-wear capacity of the Fe-based BMG can be ascribed to the high stable passivation process during wet sliding.

Microstructural and mechanical properties of a novel Al-based hybrid composite reinforced with metallic glass and ceramic particles

A new type of Fe-based metallic glass (FMG) and SiC reinforced hybrid composite was successfully developed. The current work was set to evaluate the microstructure and mechanical properties of the hybrid composite consolidated through the spark plasma sintering (SPS) process. The densities of the samples were determined in order to examine the performance of the sintering process. The experimental results indicated that, in the composites having larger amounts of FMG particles, the reinforcements/matrix interfaces were free from any discontinuities. The quantitative analysis of microstructural features revealed that the more homogenous distribution of reinforcing particles was occurred for FMG rich composites. The microstructural analysis of the samples pointed that the amorphous structure of the FMG reinforcement remained unchanged and no interfacial chemical products were created in the consolidated samples. It was also found that using FMG along with SiC particles in the samples led to the more strengthening of the Al matrix compared to using just one type of reinforcement particles. In the current study, the hybrid composite reinforced with 7 vol% of FMG and 3 vol% of SiC particles demonstrated the optimum combination of compressive yield strength (98 MPa) and strain to fracture (62.8%). The strengthening mechanisms in all the consolidated samples were calculated quantitatively considering the load bearing of reinforcing particles, grain boundary and strain hardening mechanisms. The strain hardening with the contribution of about 30% in the yield strength was the predominant strengthening mechanism in the composite samples. Also, there was a reasonable agreement between the calculated and experimentally obtained yield strength for hybrid composite samples.

Metallic glass thin film integrated with flexible membrane for electromagnetic micropump application

In this work, metallic glass (MG) thin film integrated with flexible membrane for use in an electromagnetic micropump was proposed and developed. Fe-based MG thin film deposited on a flexible membrane was employed as the actuation membrane. The electromagnetic force generated between the electromagnetic coil and the magnetized thin film was used to excite the actuation membrane. The actuation membrane was integrated with a microchannel for the micropump application. The fluid in the microchannel was driven by the pressure change resulting from the membrane deflection. Membrane deflection of 45 μm was achieved when a current of 0.12 A was applied to the electromagnetic coil. In addition, a maximum flow rate of 0.17 μl min−1 was achieved and driven by the electromagnetic micropump. The Fe-based MG integrated with the flexible membrane actuated by electromagnetic force could be applied to the actuation membrane for the electromagnetic micropump.

Selective laser melting of crack-free Fe-based bulk metallic glass via chessboard scanning strategy

Fe-based bulk metallic glass shows superior mechanical, chemical and physical properties, but its inherent brittleness and micro-cracks hinder further applications. In this paper, a novel chessboard scanning strategy combined with laser re-melting was introduced to overcome the micro-cracks of Fe-based bulk metallic glass via selective laser melting (SLM). The chessboard scanning combied with laser re-melting strategy decreases the residual stress to 168 MPa, which is only 29% of that by traditional scaning strategy. This work provides a feasible route to process crack-free Fe-based bulk metallic glass components by using SLM.

Bending ductility of stress-relieved Fe–Zr–B metallic glasses with pronounced β-relaxation

Abstract Fe-based metallic glasses are known to have excellent soft magnetic properties, but restricted to the disastrous annealing embrittlement. A novel class of Fe84-xB14+x Zr2 (x = 0, 3, 6) metallic glasses with extraordinary annealing bending ductility and excellent soft magnetic properties were developed. The metallic glasses exhibit a high BS of 1.54–1.64 T and a low HC of 4.1–5.8 A/m. It is noteworthy that the Fe84B14Zr2 metallic glass exhibits the highest ductile to brittle transition temperature among all Fe-based metallic glasses reported to date and the ductile to brittle transition temperature decreases with the decrease of Fe content. Moreover, the well-distributed shear bands can still be formed during bending for Fe84B14Zr2 metallic glass after 680 K annealing. Pronounced β-relaxation peak has been observed for Fe84B14Zr2 metallic glass in its relaxation spectra. We demonstrate that the bending deformation ability is closely correlated to the β-relaxation. The underlying mechanism for the extraordinary bending deformation ability of Fe84B14Zr2 metallic glass after annealing can be attributed to the heterogeneous structure with plenty of loosely packed zones as revealed by the pronounced β-relaxation and high resolution transmission electron microscopy.