Novel Fe‐Based Amorphous Brazing Foils in the Quinary System Fe–Ni–Cr–Si–B

Amorphous brazing foils are increasingly used on a wide variety of component geometries because of their flexibility and the resulting ease of application. Due to the recent rapid rise in Ni prices, there is an enormous need for research into the substitution of nickel with iron within conventionally used nickel‐based amorphous brazing foils. To avoid time‐consuming series of experiments, newly developed thermodynamic databases will be used to predict alloy compositions with a high glass forming ability. Foils should be produced with the melt‐spin process and characterized with differential scanning calorimetry and secondary electron microscopy. Novel iron‐based brazing foils with different compositions are successfully produced in the alloying system iron–nickel–chromium–silicon–boron. The characterization of these foils indicates the presence of a partly amorphous or nanocrystalline structure. The novel iron‐based brazing foils are characterized by a simple and cost‐efficient alloying concept. Furthermore, newly developed thermodynamic databases in the iron–nickel–chromium–silicon–boron system are validated by the successful production of these foils. The prediction of further iron‐based amorphous foils with the aid of thermodynamic calculations can thus be made possible.


Introduction
Brazing can be used to produce material-to-material joints based on the diffusion of elements between the brazing material and the base material.These joints have good strength properties and can therefore be used to join highly demanding steel components, for example, in the chemical or food industry. [1,2]n addition to precious expensive metals, such as Au and Ag, brazing is mainly carried out using Cu-or Ni-based brazing alloys.Cu-based brazing alloys have good brazing properties such as wetting or gap filling capacity, but they are less resistant to high temperatures and corrosion than Ni-based alloys.Ni-based alloys, on the other hand, have very good high-temperature properties and are therefore preferred in turbine construction. [3]Due to the rising raw material price of Ni, which has risen about 275% in between December 2018 and December 2022, [4] and the high energy requirements that have to be provided for Ni production, [5] Fe-based brazing alloys are increasingly becoming the focus of research.Both Feand Ni-based brazing alloys require the addition of melting point lowering elements such as B, P, or Si, so that the thermal influence on the substrate is kept to a minimum during the brazing process.These melting point depressants form hard and brittle phases in the form of borides, phosphides, and silicides, which make it impossible to produce brazing foils by hot or cold rolling. [6,7]o meet the increasing demand for Fe-based brazing alloys, new Fe-based brazing alloys have already been designed and their mechanical and corrosive properties were investigated. [8,9]These Fe-based brazing alloys are available as powders, which brings numerous disadvantages, like the use of environmentally harmful binder, oxidation due to the volume-to-surface ratio, and problems with application on complex component geometries. [10]For Nibased brazing alloys, amorphous foils, produced by rapid solidification, are available to overcome the problems that occur by using powders as brazing filler material.These foils are flexible and can be adapted to a wide variety of component geometries without any problems, do not require the use of binders, and enable material savings of up to one-third compared to powders. [6]Furthermore, they offer excellent mechanical and corrosive properties. [11,12]he flexibility of these amorphous foils and the outstanding mechanical properties result from the amorphous microstructure, which unlike the 3D periodic crystalline lattice has a glass-like arrangement of atoms.These so-called metallic glasses were discovered in the 1960s by Klement et al.They detected a noncrystalline microstructure in an Au 75 Si 25 alloy produced by rapid solidification. [13]Since then, numerous other alloys based on different elements, including Fe, [14] have been developed by the rapid solidification technique.According to Cohen and Turnbull, [15] metallic glasses can be obtained with all metallic alloys as long as the critical cooling rate R c to form an amorphous structure is overcome.As this critical cooling rate R c varies for different alloys, it is technically possible to achieve an amorphous structure only for alloys with a high glass forming ability (GFA) at cooling rates of up to T : = 10 5 K s À1 . [16]The GFA is a quantitative criterion to predict whether an alloy is likely to form an amorphous microstructure, which can be described with different thermodynamic and kinetic parameters.These are helpful because the kinetic parameter R c is technically difficult to measure. [15]Thermodynamic parameters contain, for example, the atomic size difference, the chemical interaction of the atoms with each other, and the arrangement of the atoms with respect to each other. [14,17]Turnbull has pointed out that eutectic or neareutectic compositions tend to have better GFA. [18]To summarize the most important parameters for an alloy to be likely to have a high GFA, Inoue has postulated the following rules [19] : 1) number of alloying elements >3; 2) negative enthalpy of mixing of the main alloying elements; and 3) atomic size difference >12%.
The chemical composition of typical Ni-based brazing alloys builds up on the Ni-Cr-Si-B system. [20]Substituting a high amount of Ni with cost-efficient Fe would lead to a multicomponent quinary system Fe-Ni-Cr-Si-B which would fulfill the first rule of Inoue's postulated rules.Regarding Inoue's second and third rule, the quinary system Fe-Ni-Cr-Si-B should exhibit a high GFA due to the negative enthalpies of mixing ΔH mix and the atomic size differences, which are shown in Table 1.
In regard to the last rule, the atomic size difference, Egami and Waseda [21] introduced the topological instability model, which was extended to multicomponent systems by Lisboa et al. by defining the atomic mismatch factor λ. [22] While C i represents the molar fraction (mol.%),r i the solute metallic radius (nm), r a the solvent metallic radius (nm), and B to Z the different alloying elements, the atomic mismatch factor λ can be calculated using Equation (1) The atomic mismatch factor λ has already been used in the Fe-Nb-B ternary system to successfully predict the GFA. [23]an et al. [24] have compared the critical producible thickness d 2 , max up to d 2,max = 1.5 mm of Fe-based bulk metallic glasses (BMGs) with the atomic mismatch factor λ of seven different Fe-based BMGs with the result that these have an atomic mismatch factor of 0.09 < λ < 0.15.The higher the atomic mismatch factors λ in this range, the higher the maximum thickness d 2 , max that can be produced. [24]spite the large number of criteria, e.g., the atomic mismatch factor λ used to evaluate the GFA of alloys, it is difficult to narrow the window of possible alloys with a high GFA.In order to avoid a large number of trial-and-error attempts, thermodynamic simulations can be used.One method to do so is the CALculation of PHAse Diagrams (CALPHAD) method.The CALPHAD method has been developed in the 1950s and continuously complemented since then. [25]It can be used to predict alloys which are suitable for specific applications, combining experimental and theoretical knowledge of thermodynamics and physical chemistry, and thus can calculate chemical systems as a function of temperature, composition, and pressure [26,27] by minimizing the Gibbs free energy in the binary, ternary, or multicomponent systems. [28]he CALPHAD software Thermo-Calc is a suitable tool for thermodynamic modeling, which contains numerous of databases.[29] As there is no specific database especially for brazing, the SSOL [30] and TCNI [31] databases are often used in this field.The SSOL database contains a large number of binary and ternary systems, while the TCNI database for Ni superalloys contains numerous binary and ternary systems of the elements Ni, Cr, Fe, B, and Si, which are typical alloying elements in Ni-based amorphous brazing alloys.In the field of brazing, these databases are mainly used to predict phase formation within the brazing gap as well as diffusion behavior between substrate material and filler metal.Riggs et al., [32,33] for example, compared predictions made due to the DICTRA software using the TCNI17 database with experimental results regarding the phase formation of phases in the brazing gap of the Ni superalloy substrate CMSX-4 in combination with BNi-2 and BNi-9.For both joints simulated and experimental agreed quite well on the formation of intermetallic phases that form in the γ-FCC matrix of the brazing gap. Also they could use the DICTRA software to predict the maximum permitted size gap for brazing CMSX-4 and BNi-2 to complete isothermal solidification, which is better for shorter holding times.Experiments have verified the prediction.Similar studies have been done by Ruiz-Vargas et al. [34] using Thermo-Calc to predict phase formation while brazing pure Ni with BNi-2 filler metal. The found out that predictions widely agree with experimental results but the Cr content within the predicted phases is in reality significantly lower than predicted, so that quantitative predictions should be critically questioned.
Another possibility to use the CALPHAD method within the field of brazing is for filler metal design.Piegert et al. [35] designed a Ni-Mn-Si filler metal by using, besides DICTRA, the Thermo-Calc software to predict the equilibrium phases and the liquidus surface over a compositional range.So far, the use of Thermo-Calc software for designing brazing filler metals is used for binary or ternary systems.As the accuracy of the prediction of a eutectic composition in a multicomponent system increases significantly when all binary and ternary systems are fully described, [36] the ternary system Fe-Ni-Si was first fully described by the authors in previous work on this project. [37,38]hey investigated eight different alloys in the Fe-Ni-Si system and used the experimental data to complete databases.For thermodynamic modeling and optimization, they used the Gibbs energy functions from the Scientific Group Thermodata Europe (SGTE) for pure elements [39] and for substances. [40]ble 1.Enthalpies of mixing ΔH mix (kJ mol À1 ) and atomic radii (pm) of the alloy constituents in the quinary system Fe-Ni-C-Si-B. [45,46]thalpy of mixing Sublattice models can be found in previous work on this project. [37]The multicomponent quinary system Fe-Ni-Cr-Si-B has a cost-efficient alloying composition which should be suitable for brazing application.Ni and Cr are added for corrosive properties and Si and B as melting point depressants due to the existence of various amorphous brazing foils in the Ni-Cr-Si-B system. [41]The quinary system Fe-Ni-Cr-Si-B consists of ten binary and ten ternary systems listed in Table 2.
In this work, our goal is to experimentally investigate four different alloys in the multicomponent quinary system Fe-Ni-Cr-Si-B, which should be promising future candidates for cost-efficient brazing.Therefore, theses alloys should at least contain an Fe content of >50 wt%.To ensure an easy application of these alloys, they should be flexible due to their amorphous microstructure.Eutectic compositions which should exhibit a high GFA are predicted with the help of a newly developed thermodynamic database in the multicomponent quinary system Fe-Ni-Cr-Si-B.The complete database for the quinary system Fe-Ni-Cr-Si-B is still in progress and not published yet.It should be explicitly stated that the main objective of this study is to produce a flexible Fe-based brazing foil in the quinary system Fe-Ni-Cr-Si-B via rapid solidification.The proportion of the amorphous phase is secondary and is only aimed at ensuring the flexibility of the foil for easier application in the brazing process.

Experimental Section
Based on the ternary system Fe-Ni-Si that the authors characterized in a previous work, [37] a quinary database in system Fe-Ni-Cr-Si-B has now been developed, which will not be published in full.The selected compositions are to be eutectic alloys with an Fe content of >50 wt% and a Ni content of <35 wt%.The alloys investigated were selected along the eutectic reaction "Liquid ⇄ FCC-Fe þ M 2 B", while one of the solid phases is an iron-, nickel-rich solid solution with face-centered cubic crystal structure and the other (Fe,Cr) 2 B. For all investigated alloys, the computed phase equilibria as a function of temperature can be seen in Figure 1.While phase diagrams are usually presented for binary and ternary systems, as has been done in preliminary work for the characterization of the ternary system Fe-Ni-Si, [37] the presentation shown in Figure 1 is common for multicomponent systems for which the presentation of a phase diagram is hardly possible.
For the calculation of the atomic mismatch factor λ, the metallic radii listed in Table 3 and Equation (1) are used.For the metallic radius of the main alloying element r a , the metallic radius of Fe is used.
Table 4 shows seven alloys that are predicted to be eutectic or near-eutectic according to the new database.The calculated atomic mismatch factors λ is listed as well.Alloys 1-3 have already been investigated by the authors and will not be investigated in this study.The investigation of alloys 1-3 is still under submission and not published yet.The authors found out that alloy 2 has been the most successful alloy with respect to a partly amorphous or nanocrystalline microstructure.Alloy 2 has an atomic mismatch factor of λ = 0.090 which fits into Yan et al. [24] value range of 0.09 < λ < 0.15, in which the investigated Fe-based BMGs are producible.Based on the this result and the already obtained investigation results of the authors on alloys 1-3, alloy 6 with an atomic mismatch factors of λ = 0.090 should obtain the best results.
For alloy production, granules with a grain size of 1 mm < d < 5 mm and a purity of more than 99.98%, except B (99.4%), are weighed on a fine balance.The melting and homogenization of m = 10 g of each sample takes place in a p = 3 Â 10 2 mbar Ar atmosphere at an operating electric current of I = 350-450 A in the Arc Melter AM500 by Edmund Bühler GmbH.The melted alloys are then used for the melt-spin process.The Melt-Spinner SC from Edmund Bühler, schematically shown in Figure 2, can be used to produce amorphous foils on a laboratory scale.
Figure 2 shows various process variables that can be set in the melt-spin process.In the process presented here, the parameters shown in Table 5 are to be set.The wheel speed v will be varied once, while the overpressure Δp is not varied throughout the studies.Temperatures T are selected in regard to the calculated liquidus temperature T l,calc and will be set ΔT = 50 K and ΔT = 100 K above T l,calc .Because alloy 6 has been successful in regard to flexibility at first try, the distance between copper wheel and crucible d 1 will be varied.The higher this distance, the slower is the cooling process.For alloy 6, it should be investigated whether it can be produced at slower cooling rates.
After the melt-spin process, the foils are subjected to a differential scanning calorimetry (DSC) measurement so that the calculated and experimental melting points can be compared and any solid phase transitions from amorphous to crystalline can be detected.The DSC system SETARAM SETSYS Evolution from Setaram Instruments is used for this purpose.Two heating cycles are run to validate the data.Material of a quantity of approx.m = 0.010 g is placed in an Al 2 O 3 crucible for DSC measurement.Heating from room temperature to T end = 1300 °C takes place at a heating rate of T : heat = 0.17 K s À1 .This is followed by cooling to T mid = 200 °C with T : cooling = 0.25 K s À1 and then heating again.To investigate the microstructure of the alloy in addition to the melting behavior, X-ray diffraction (XRD) with the diffractometer C3000 from GE Energy Germany GmbH is performed.To do so Co Kα is used  126.0 [56] 124.4 [56] 126.7 [56] 117.3 [56] 98.0 [56] Table 4. Calculated chemical composition of seven eutectic Fe-based alloys in the quinary system Fe-Ni-Cr-Si-B with calculated liquidus temperature and atomic mismatch factor λ.   [44] electron-dispersive spectroscopy (EDS), a wet chemical analysis of one of the produced foils is carried out.

Melt-Spin Process
Temperature measurement during the homogenization in the BN crucible was not possible due to high-temperature variation.
We assume that the liquid melt was drawn to the edge of the crucible by the inductive heating and that the temperature measurement by means of a pyrometer in the center of the crucible was therefore not possible.
Figure 3 shows alloy 4 after the melt-spin process with different process parameters.Only alloy 4.3 with a thickness of about d 2 = 30 μm has been successful.While alloys 4.1 and 4.2 are brittle, alloy 4.3 is a flexible foil with only few imperfections, like longitudinal cracks and a good cuttability, which is advantageous for the brazing process.The chemical composition of alloy 4 is advantageous for brazing stainless steel because the Cr content is high.That avoids a Cr concentration gradient between substrate and alloy 4 during brazing.Also, the concentration of melting point depressants is low in comparison to the other investigated alloys which counteracts the undesirable formation of hard brittle phases like silicides and borides during the brazing process.
The results for alloy 5 are shown in Figure 4. Optically alloys 5.1 and 5.2 are the worst results out of every selected alloy.In contrast to this, alloy 5.3 is optically the best foil which has also a thickness of d 2 = 30 μm.No imperfections are seen here, but intensive bending leads to cracking.Cuttability is given but the edges are more fragile in comparison to alloy 4.3.In regard to future brazing tests, alloy 5.3 has a good chemical composition because the Cr content is high and the amount of melting point depressants is acceptable.Out of every alloy this one should be the most cost-efficient because the Fe content is the highest, leading to the lowest Ni content.Nevertheless, brazing would be difficult due to the high liquidus temperature T l,calc = 1270 °C of alloy 5. Brazing processes must be carried out at least at T B = 1300 °C.
Alloy 6 is the most successful alloy in regard to reproducibility as shown in Figure 5.With the first investigated process parameters, a flexible foil, alloy 6, could be produced directly.Even with   Figure 6 shows alloy 7, which also has a thickness d 2 = 30 μm.All three samples are flexible and do not crack under intensive bending, but they show a lot of longitudinal cracks within the foil.Every foil has a good cuttability with straight edges.The chemical composition is suitable for brazing substrates with a lower Cr content.Especially the low B content can prevent the formation of Cr borides on grain boundaries in the diffusion zone of the substrate and a Cr depletion in the grains.The Si content is the highest of every investigated alloy, which is disadvantageous in regard to the formation of brittle silicide phases within the brazing gap.For alloy 7, the calculated atomic mismatch factor of λ = 0.054 is the lowest, although the foil is flexible.Here, further investigations on the amorphability of alloy 7 need to be performed to validate or falsify the accuracy of the atomic mismatch factor λ for predicting the GFA in the quinary system Fe-Ni-Cr-Si-B.

Differential Scanning Calorimetry
Analysis on the thermal behavior of the investigated alloys is performed to compare experimental and calculated data.Also, DSC measurement can show exothermic peaks which indicate the presence of an amorphous phase within the alloys.Because alloy 6 is the most successful foil in regard to flexibility, results of the DSC measurement of alloy 6 are shown in Figure 7. Every first heating cycle shows exothermic peaks indicating a solid phase transformation in the temperature range of about 420 °C < T Rx < 510 °C for alloy 6.This is probably the transitions from amorphous to crystalline microstructure.The glass transition temperature T g can usually be identified as a shallow endothermic peak preceding the exothermic transformation peaks. [42]is is mostly not identifiable in Fe-based amorphous alloys because there is often an overlap of the endothermic and exothermic recrystallization peaks. [43]No exothermic peaks can be observed in the second heating processes because crystalline alloys are present here after the first heating process.This result also speaks for the presence of a partly amorphous microstructure of the produced foil.Here, the results for the highest investigated d 1 are the best because the intensities of the peaks are higher, indicating a larger amount of amorphous phase within alloy 6.3 compared to alloys 6.1 and 6.2.
In Table 6, the experimental and computed data of the melting intervals for every investigated alloy are compared.For alloys 4, 5, and 7, there are high discrepancies between the melting intervals within the three tested samples.This could already be seen by the difference in optical appearance of the foils after the melt-spin process.Problematic hereby is that the adjustment of temperature during the melt-spin process was not feasible which could have led to the premature leakage of melt from the BN crucible during the homogenization process.Segregation of alloying elements is possible in the process.Only very few amounts of material are tested in the DSC measurement, so that the tested material may not be representative for the complete foil, which consists of various phases if it is not completely amorphous.For alloy 6, the experimental data of the three investigated samples fit quite well.Exothermic peaks are seen for alloy 5.2, which is optically not a good result, for all samples of alloy 6 and alloys 7.2 and 7.3.These peaks are an indicator of partly amorphous phases within these alloys.Regarding the DSC measurement, the atomic mismatch factor λ is not suitable for predicting the GFA of the investigated alloys.While alloy 6 produced the best results and, appropriately, had the best atomic mismatch factor, alloy 7, with the lowest atomic mismatch factor, was significantly more successful in terms of flexibility, cuttability, and evidence of a partially amorphous structure than alloys 4 and 5.In tendency, the computed liquidus temperatures are significantly higher than the experimental data, so adjustment of the database is part of future work.The thermodynamic databases have to be improved though.

XRD Analysis
XRD measurements of selected foils were carried out to characterize the microstructure.Alloys 4.3, 5.3, 6.1, and 7.3 were analyzed, as they were produced with the same process parameters in the melt-spin process and can therefore be compared.Alloy 6.3 provided the best optical result in the melt-spin process and will therefore also be investigated by XRD measurement.Figure 8 shows the corresponding results.All alloys have the peak with the highest intensity at γ-Ni (ICDD 00-004-0850).Slight shifts may be due to the other alloying elements.Furthermore, overlaps with Fe 2 B (ICDD 00-036-1332) can be observed.Both phases were predicted by Thermo-Calc, so this result contributes to the validation of the newly developed thermodynamic database in the quinary system Fe-Ni-Cr-Si-B.Other overlapping peaks are γ-Fe (ICDD 01-071-4407) and CrB 2 (01-089-3533).It can be seen that the peaks become more and more diffuse in an ascending order from alloy 4 to alloy 7. Especially for alloys 6 and 7, broad peaks can be observed, indicating an amorphous fraction within the microstructure.As already shown by the exothermic peaks of the DSC measurement and the results after the melt-spin process, the foils with the highest flexibility are the foils that show the most indicators of an amorphous phase within the microstructure.

Microstructure Analysis
To further investigate the morphology of the selected alloys, SEM images at different magnifications have been taken.Figure 9 shows the SEM images of alloy 4.3.Although at least alloy 4.3 is flexible and has a good cuttability, it shows no signs of a partly amorphous structure in both DSC measurements and SEM images.The SEM image clearly shows different morphologies which indicates a completely crystalline morphology in the viewed areas of the foil.For alloy 4.3, the microstructure is probably eutectic due to the globular dendrites.
In Figure 10, the microstructure of alloy 5 is shown.Alloy 5.3, which resulted in the best foil, has a very fine microstructure, which is hardly visible.Dendrites are more globular indicating a eutectic microstructure.All samples of alloy 6 look similar to each other due to the good reproducibility of this foil.As Figure 11 shows, no morphologies are visible, indicating an amorphous microstructure, while the probability of the existence of an amorphous phase should be the highest of all tested compositions regarding the atomic mismatch factor λ. DSC measurement and flexibility   of alloy 6 gives hint to the existence of an amorphous phase, especially for alloy 6.3 with the highest intensities for the solid phase transition amorphous to crystalline.As alloy 6 is flexible and this was the aim of the investigations, further investigations into the proportion of amorphous microstructure are not necessary.
The possibility for alloy 7 to be partly amorphous should be the lowest in regard to the atomic mismatch factor λ. Nevertheless, DSC measurement and SEM images of alloy 7.3, Figure 12, make it seem that alloy 7 has the highest probability after alloy 6, to contain partly amorphous microstructure.
The chemical composition of the investigated alloys cannot be measured by SEM/EDS analysis because B is too small to be quantitatively determined here.For this reason, a wet chemical analysis is carried out with approx.m = 3-4 g of alloys 4.3, 5.3, 6.1, and 7.3, which were produced with the same process parameters.The results can be seen in Table 7.The nominal and actual compositions agree well with each other in regard to Ni and Cr.For Fe, Si, and B, the differences between nominal and actual composition differ more.One reason for this could be the usage of a BN-crucible.B could possibly dissolve in the Fe-based melt, causing a higher B-content that excepted.Nevertheless, the microstructure of the investigated alloys seems to be eutectic, resp.amorphous, and there are exothermic peaks in the DSC measurements, indicating a solid phase transformation from amorphous to crystalline.So the differences in nominal and actual composition have not influenced the successful production of an Fe-based flexible foil.

Summary and Conclusion
Due to the rising price of Ni and the environmentally harmful extraction process of Ni, the demand for cost-efficient Fe-based alloys in the field of brazing is increasing.Complex alloy design in the form of trial and error can be simplified and shortened by using thermodynamic simulation.In this study, four Fe-based alloys were prepared by the melt-spin process and subsequently characterized.According to the prediction of a newly developed thermodynamic database, which is not published yet, these four Fe-based alloys in the quinary multicomponent system Fe-Ni-Cr-Si-B are near-eutectic and thus exhibit a high glass-forming ability.An amorphous microstructure of the alloys should be aimed at, so that they are as flexible as possible and ensure easy application for later use in the brazing process.The main objective was thus to produce a flexible foil by means of a melt-spin process, which has a cost-effective alloy concept with an Fe content of >50 wt%.The amorphous microstructure was merely a means to an end, so that its contribution to the microstructure is of secondary importance and was not characterized in detail.One of the alloys investigated was successfully produced without defects using the melt-spin process.Based on its flexibility and the results of differential scanning calorimetry, this alloy shows signs of an amorphous microstructure and thus confirms the predictions of the unpublished thermodynamic database.Future brazing tests with the newly developed Fe-based foil will be carried out to characterize the formation of the microstructure within the brazing gap and in the diffusion zone.The definition

Table 2 .
List of ten binary and ten ternary systems that could be derived out of the quinary system Fe-Ni-Cr-Si-B including the literature reference and the status of modeling completeness.as a radiation source, the voltage is set to U = 40 kV, and the current to I = 40 mA.For further investigation, scanning electron microscopy (SEM) images are taken in backscatter secondary electron (BSE) mode using the PhenomX desktop SEM from Thermo Fisher GmbH.The accelerating voltage is set to U = 20 kV.As it is not possible to investigate the chemical composition of B-containing materials quantitatively with

Figure 1 .
Figure 1.Computed phase equilibria as function of temperature using the proprietary database for the iron-nickel-chromium-silicon-boron alloy system.The calculations clearly show that solidification proceeds along the eutectic reactions "Liquid !Fe_FCC þ Cr 2 B" for alloy 4 a), alloy 5 b) and alloy 7 d) and "Liquid !Fe_FCC þ Fe 2 B" for alloy 2 c), respectively.

Figure 2 .
Figure 2. Schematic figure of the Melt-Spinner SC from Edmund Bühler on a laboratory scale.[44]

Table 7 .
Comparison between nominal and actual chemical composition of the calculated eutectic alloys in the quinary system Fe-Ni-Cr-Si-B.a suitable process route specifically for the newly developed Febased foil should help to achieve the best possible mechanical properties that can compete with conventional Ni-based brazing alloys. of