Clean production of Fe-based amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore and apatite

Separated preparation of prealloys and amorphous alloys results in severe solidification-remelting and beneficial element removal-readdition contradictions,which markedly increase energy consumption and emissions.This study offered a novel strategy for the direct production of FePC amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore(HPIO)and apatite.First,the thermodynamic conditions and equilibrium states of the carbothermal reduction reactions in HPIO were calculated,and the element content in reduced alloys was theoretically determined.The phase and structural evolutions,as well as element migration and enrichment behaviors during the smelting reduction of HPIO and Ca_(3)(PO_(4))_(2),were then experimentally verified.The addition of Ca_(3)(PO_(4))_(2)in HPIO contributes to the enrichment of the P element in reduced alloys and the subsequent development of Fe_(3)P and Fe_(2)P phases.The content of P and C elements in the range of 1.52 wt% -14.63 wt% and 0.62 wt% -2.47 wt%,respectively,can be well tailored by adding 0-50 g Ca_(3)(PO_(4))_(2)and controlling the C/O mole ratio of 0.8-1.1,which is highly consistent with the calculated results.These FePC alloys were then successfully formed into amorphous ribbons and rods.The energy consumption of the proposed strategy was estimated to be 2.00×10^(8) kJ/t,which is reduced by 30% when compared with the conventional production process.These results are critical for the comprehensive utilization of mineral resources and pave the way for the clean production of Fe-based amorphous soft magnetic alloys.

Formation and mechanical properties of ductile Fe-based amorphous alloys using a cast iron with minor addition of B and Al

Fe-based amorphous alloys with ductility were synthesized using the commercial cast iron QT50 (denoted as QT) with the combining minor addition of B and Al by single roller melt-spinning. The melt-spun (QT1-xBx)99Al1 (x is from 0.006wt% to 0.01wt%) amorphous alloys exhibit onset crystallization temperatures and Curie temperatures of 759-780 and 629-642 K respectively, and whi- ch increase with B content. The amorphous ribbons are ductile and can be bent 180° without breaking. With the increase in B content from 0.006wt% to 0.01wt%, the Vickers microhardness of the amorphous alloys increases from Hv 830 to Hv 1110. The effects of the additional B and Al elements on the glass forming ability and mechanical properties were also discussed.

Ab initio molecular dynamics simulations of nano-crystallization of Fe-based amorphous alloys with early transition metals

The addition of early transition metals(ETMs)into Fe-based amorphous alloys is practically found to be effective in reducing theα-Fe grain size in crystallization process.In this paper,by using ab initio molecular dynamics simulations,the mechanism of the effect of two typical ETMs(Nb and W)on nano-crystallization is studied.It is found that the diffusion ability in amorphous alloy is mainly determined by the bonding energy of the atom rather than the size or weight of the atom.The alloying of B dramatically reduces the diffusion ability of the ETM atoms,which prevents the supply of Fe near the grain surface and consequently suppresses the growth ofα-Fe grains.Moreover,the difference in grain refining effectiveness between Nb and W could be attributed to the larger bonding energy between Nb and B than that between W and B.

Ferromagnetic Fe-based Amorphous Alloy with High Glass-forming Ability

A ferromagnetic amorphous Fe73Al4Ge2Nb1P10C6B4 alloy with high glass-forming ability was synthesized by melt spinning. The supercooled liquid region before crystallization reaches about 65.7 K. The crystallized structure consists of alpha -Fe, Fe3B, FeB, Fe3P and Fe3C phases. The Fe-based amorphous alloy exhibits good magnetic properties with a high saturation magnetization and a low saturated magnetostriction. The crystallization leads to an obvious decrease in the soft magnetic properties.

Effect of Y element on atomic structure, glass forming ability,and magnetic properties of FeBC alloy

The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-forming ability and magnetic properties of Fe_(86-x)Y_xB_7C_7(x = 0, 5, 10 at.%) amorphous alloys via both experiments and ab initio molecular dynamics simulations. Furthermore, we explore the correlation between local atomic structures and properties. Our results demonstrate that an increased Y content in the alloys leads to a higher proportion of icosahedral clusters, which can potentially enhance both glass-forming ability and thermal stability. These findings have been experimentally validated. The analysis of the electron energy density and magnetic moment of the alloy reveals that the addition of Y leads to hybridization between Y-4d and Fe-3d orbitals, resulting in a reduction in ferromagnetic coupling between Fe atoms. This subsequently reduces the magnetic moment of Fe atoms as well as the total magnetic moment of the system, which is consistent with experimental results. The results could help understand the relationship between atomic structure and magnetic property,and providing valuable insights for enhancing the performance of metallic glasses in industrial applications.

Preparation of Plate Fe_(60)Co_8Zr_(10)Mo_5W_2B_(15) Bulk Amorphous Alloy and Its Fracture Toughness

With processes of arc melting, inductive melting and copper mold suction casting, a plate Fe-based bulk amorphous alloy Fe_(60)Co_8Zr_(10)Mo_5W_2B_(15) with a thickness of 1mm was prepared. The surfaces and fractures of the cast bulk amorphous alloy were agleam and with typical metallic luster. The glass transition temperature(T_g), supercooled liquid region(△T_x)and reduced glass transition temperature(T_(rg))of the prepared Fe-based amorphous alloy are 884 K,63 K, and 0.611 respectively. The fracture toughness of the cast bulk amorphous alloy is at the level of 1.6 MPa·m^(1/2).

INFLECTION OF COERCIVITY DURING LOCAL CRYSTALLIZATION OF Fe-Si-B AMORPHOUS ALLOYS

An inflection hehaviour was revealed during isothermal annealing under the observation of transition of the coercivity of Fe-Si-B amorphous alloys during local crystallization.It may be interpreted by the transition of α-Fe grain precipitated from single to multiple domain, Thus,the theoretical expression of H_0-t_a may be derived.The plot of expression H_0-t_a calcu- lated well represents the feature of the experimental curve.

The irradiation variation of amorphous alloy FeSiB using for fusion devices induced by 2 MeV He ions

Because of its unique long range disordered structure and numerous free volume,amorphous alloy is considered to be able to accommodate the damage caused by ion bombardment and has good irradiation resistance.2 MeV He+ions were selected to irradiate amorphous alloy Fe80Si7B13,and it was found that the arrangement of atoms in the amorphous alloy became uneven.In the bubble layer located near the He ion range which was about 3.5μm from the surface,the local atoms had a tendency of ordered arrangement.Under the irradiation,no obvious damage could be observed on the surface of the amorphous alloy,while the surface roughness increased,which reduced the surface relative reflectivity of the amorphous alloy.After the irradiation,the Fe-based amorphous alloy maintained the soft magnetic performance.The variation of atomic arrangement in the amorphous alloy enhanced its saturation magnetic induction intensity.

Hot corrosion behaviors of 921A alloy and HVAF-sprayed Fe-based amorphous coating covered with KCl-ZnCl_(2) salts

Hot corrosion behaviors of the 921A alloy and Fe-based amorphous coating induced by KCl-10% ZnCl_(2) and KCl-55% ZnCl_(2) salts at 450℃ in air for 40 h were investigated.Results show that the 921A alloy suffers more serious corrosion damage than the coating and KCl-55% ZnCl_(2) salts are more corrosive than KCl-10% ZnCl_(2) salts.In the two salts,an Fe_(2)O_(3) layer is formed on the 921A alloy surface,while an outer Fe-rich oxide layer and an inner Cr-rich oxide layer are formed on the surface of the coating.Moreover,a certain amount of metal chloride can be found at the oxide/alloy(coating)interface,which can be explained by "active oxidation".However,the corrosion resistance of the Fe-based amorphous coating did not achieve the desired results,probably because the intersplats in the coating serve as corrosion diffusing channels,which facilitate the corrosion damage rate.Nevertheless,the coating is still in amorphous state after hot corrosion exposure.

Purifying Fe-based amorphous alloys to enhance glass-forming ability by designing a novel refining slag

Designing low melting point and low basicity refining slag suitable for Fe-based amorphous alloys and understanding the inclusions’formation,removal,influencing mechanisms are quite vital in the fields of metallurgy and materials.In this study,a novel 13%SiO_(2)-32%CaO-30%Al_(2)O_(3)-25%B_(2)O_(3)(wt.%)refining slag was designed after careful calculations of the liquid phase region,slag-metal equilibrium,surface tension,viscosity,deoxidation capability and sulfur distribution ratio.After refining with our designed slag,the content of impurities and the number density of inclusions in a representative Fe_(83)Si_(2)B_(15)(at.%)amor-phous alloy were significantly reduced.Moreover,the glass-forming ability(GFA)of the alloy was also enhanced,enabling the preparation of amorphous ribbons with a lower cooling rate.Based on the impu-rities in Fe-based amorphous alloys as well as the calculated oxide and sulfide free energy diagrams,CaO,SiO_(2),Al_(2)O_(3) oxides and CaS,TiS,MnS sulfides will form in the master alloy.The high melting point in-clusions in the melt are generally removed via a floatation-separation-absorption process and the Mn,Ti,S impurities are removed via slag-metal interface reactions during refining.As for the detrimental effect of inclusions on glass formation,the small lattice disregistry between Ti,Mn-containing inclusions and primaryα-Fe gains reveal that these inclusions are effective in promoting the heterogeneous nucleation,and therefore greatly deteriorate the GFA.These findings are important and provide an ideal solution to purifying the Fe-based amorphous alloys by refining and enhancing the GFA for industrial production.

Process-structure-property relationship for plasma-sprayed iron-based amorphous/crystalline composite coatings

This study explores the fabrication of Fe-based amorphous/crystalline coating by air plasma spraying and its dependency on the coating parameters(plasma power,primary gas flow rate,powder feed rate,and stand-off distance).X-ray diffraction of the coatings deposited at optimized spray parameters showed the presence of amorphous/crystalline phase.Coatings deposited at a lower plasma power and highest gas flow rate exhibited better density,hardness,and wear resistance.All coatings demonstrated equally good resistance against the corrosive environment(3.5wt%NaCl solution).Mechanical,wear,and tribological studies indicated that a single process parameter optimization cannot provide good coating performance;instead,all process parameters have a unique role in defining better properties for the coating by con-trolling the in-flight particle temperature and velocity profile,followed by the cooling pattern of molten droplet before impingement on the substrate.

Fe-based bulk amorphous alloys with high glass formation ability and high saturation magnetization

It was well known that it was very difficult to prepare high performance Fe-based bulk amorphous alloys with both high Fe content and good glass-forming ability, especially for the Fe content （or total magnetic elements content） higher than 80 at%. In this paper, a series of Fe81-xCoxMO1P7.5C5.5B2Si3 （x = 0, 5, 10, 15, 20） bulk amorphous alloys （BAAs） with high saturation magnetization have been developed by copper mold casting method with fluxed ingot. It has been found that using Co replacing Fe in the Fe-Mo-P-C-B-Si alloy could significantly enhance the glass-forming ability and magnetic property. For the BAA with Co content of 0 at%, 5 at%, 10 at%, 15 at% and 20 at%, its saturation magnetization Js（Js=μoMs） was 1.55, 1.60, 1.62, 1.65 and 1.59 T, respectively. Among these alloys, the Fe66Co15- Mo1P7.5C5.5B2Si3 BAA exhibited a critical size of 2 mm in diameter and a high Js of 1.65 T. It suggested that these alloys with high magnetic element content possessed great potential in application due to their high glass-forming ability and high magnetic property.

Improvement of giant magneto impedance of Co-rich melt extraction wires by stress-current annealing

In order to improve the giant magneto impedance （GMI） of Co-rich wires for high sensitive sensor applications, Co6sFe4.sSilsBlz5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile slresses applied. And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz. It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments, because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy, which improved the circular permeability and GMI effect. Their impedance ratio AZ/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/（A/m） at 5 MHz, when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min. It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.

A PASSIVATION STUDY OF Ti-MODIFIED Fe—BASE ALLOY SYNTHESIZED BY MAGNETRON SPUTTERING TECHNIQUE

A set of fracture device was designed on the basis of traditional scratching-electrode technology and used to study the passivation process of two magnetron-sputtered stainless sleel coatings (amorphous and crystalline struture). The results of fracture tests in 3.5 % NaCl aqueous solution show that the amorphous alloy has a high bare surface reactivity and a high passive rate in comparison with the crystalline alloy. The effect of structure on corrosion resistance is also discussed. The excellent corrosion resistance of amorphous alloy is considered to be partly attributed to its great passivation ability.

Effect of Spark Plasma Sintering on Microstructures and Properties of Al-Fe Alloy

2024 Aluminum alloy powder( 60wt%) and Fe-based amorphous powder( 40 wt%) were adopted. They were mechanical machined for 48hours after being mixed. Bulk material was gained after Spark Plasma Sintering. The sintering parameters included sintering temperature,heating or cooling rates,pressure and holding time. 300 ℃- 800 ℃ were adopted while the heating or cooling rate was 100 ℃ / min and with the pressure of 50 MPa in the experiments. The holding time was 10 min or 20 min at different temperatures, respectively. Bulk materials after sintering were examined by Scanning Electron Microscopy and X-Ray Diffraction. The micro-hardness and relative density also were tested. The sintering temperature had the most significant influence on the microstructure and property of the bulk material. The influence of holding time came second while the heating or cooling rates and pressure were fixed. The density became larger with the increase of the temperature. The compactness was best at 500℃. The pressure and generation of high-temperature phases were the factors which affected the density and the compactness.

Preparation and Study of the Crystallization Behavior of the Fe87Zr7B5-x Nanocristalline Soft-Magnetic Alloys

A series of materials of composition Fe87Zr7B6,Fe87Zr7B5Ag1,Fe87Zr7B5Cu1 have been prepared by the melt spinning method for different cooling speed to get completely or partly amorphous ribbons.It is proved that the crystallization process is composed of 2 steps.The first step is the precipitation of&-Fe only and the second step is the phase separation of&-Fe,Fe2Zr and Fe2B.All our own made materials have been used in the library monitoring system.Most of them showed a capability of triggling the alarm of the system.The triggling sensitivity at different positions and different sample geometry were investigated and the physical mechanisms were analyzed.

In situ X-ray diffraction study of structural evaluation in Fe_(73)Cu_(1.5)Nd_3Si_(13.5)B_9 amorphous alloy at high temperature

The thermodynamics structural relaxation of Fe73Cu1.5Nd3Si13.5B9 amorphous alloy from room temperature to 400℃ has been investigated by measuring the structure factor with in situ X-ray diffraction. The structural information of the atomic con-figuration such as radial distribution function (RDF) and neighbor atomic distance was gained by Fourier transformation. The research result shows that the amor-phous structure remains stable in the temperature range of 30 to 400℃ but exhibits distinct changes in local atomic configuration with the increase of temperature. The quantitative determination of the neighbor atomic distance suggests that the de-gree of short-range order changes by the temperature altering the second nearest neighbor local atomic configuration of the amorphous when structural relaxation occurs.

Laser Surface Remelting of Fe-based Alloy Coating Deposited by APS

The Fe-based amorphous alloy coatings with different porosities were deposited on Q235 steel substrates by means of atmospheric plasma spraying(APS).The as-sprayed coatings were remelted by the facility of a Nd:YAG laser to further enhance their compactness and bonding strength via orthogonal experiment design.The effects of laser remelting on the microstructure,phase compositions and mechanical properties of the as-sprayed coatings were investigated by optical microscopy,scanning electron microscope,X-ray diffraction and Vickers microhardness tester.The corrosion performance of the coatings was evaluated by both potential dynamic measurements(PDM)and electrochemical impedance spectroscopy(EIS)in a 10%NaOH solution.The results indicate that laser power of 700 W,scanning velocity of 4 mm/s,beam size of 3 mm and porosity of 1.19%are the optimized remelting process parameters.The laser-remelted coatings exhibite more homogenous structure as strong metallurgical bonding to substrates.The amorphous phases in the as-sprayed coatings crystallize toα-Fe,Fe2Si,Fe3.5B,and Fe2W phases for the high temperature and rapid solidification in the remelting process.The microhardness values of as-sprayed are in the range of 700-800 HV0.1,while the microhardness values of the remelted coatings are enhanced slightly to 750-850 HV0.1.Both PDM and EIS analysis results show that the remelted coatings exhibite relatively excellent corrosion resistance compared with the stainless steel 1Cr18Ni9Ti,however the corrosion resistance of the remelted coatings is inferior to the as-sprayed amorphous coatings.

Excellent magnetic softness-magnetization synergy and suppressed defect activation in soft magnetic amorphous alloys by magnetic field annealing

Fe-based amorphous alloys with high saturation magnetic flux density(B_(s))are increasingly attractive from both scientific and technological points of view,however,they usually suffer from the trade-off between magnetization and softness.In this work,we explore the soft magnetic properties(SMPs),magnetic and atomic structures,and defect activation during creep deformation of as-quenched and annealed Fe_(82.65-x)Co_(x)Si_(2)B_(14)Cu_(1.35)(x=0-20)amorphous alloys(AAs).Improved magnetic softness-magnetization synergy has been realized in all these alloys by field annealing.Particularly,superb SMPs with superhigh B_(s) of 1.86 T,low coercivity of 1.2 A/m and high effective permeability of 16300 are obtained in the Fe_(66.65)Co_(16)Si_(2)B_(14)Cu_(1.35) AA.The locally regularized arrangement of domains,homogenized structure with less structural/magnetic defects and suppressed crystal-like ordering by field annealing contribute synergistically to the superb SMPs.Besides,the relaxation time spectra obtained from creep deformation indicate less liquid-like and solid-like defects activated in the field-annealed AA,which is correlated with the structural homogenization and superb SMPs.This work provides new and comprehensive insight into the interplay among external field,heterogeneous structure,SMPs and defect activation of Fe-based AAs,and offers a promising pathway for softening amorphous alloys with high Bs.

Influences of preparation techniques on glass-forming ability of Fe-P-B-Si-C amorphous alloys

It has been widely accepted that the ultrafast cooling rate is required for the glass formation of amorphous alloys. Here, the larger glass-forming ability （GFA） of Fe76P5（B0.5Si0.3C0.2）19 amorphous alloy was achieved by water quenching at lower cooling rate under argon atmosphere. Cylindrical rods with diameters of 1-2 mm were prepared by water quenching without flux treatment, Cu-mold injection casting, and Cu-mold suction casting, respectively. The influences of the preparation techniques with different cooling rates on GFA, thermal property, and nucleation/growth behavior were examined. The critical diameter of the Fe76P5（B0.5Si0.3C0.2）19 amorphous alloys is 1.7 mm for water quenching while smaller than 1.0 mm for injection casting. Microstructure analysis indicates that the crystallization and solidification processes are quite different between the water-quenched and the injection-cast rods. These findings could deepen fun-damental understanding on the relationship between the cooling rate, techniques, and GFA of Fe-based amorphous alloys.