Next Article in Journal
Enhancing the Strength and Toughness of A356.2-0.15Fe Aluminum Alloy by Trace Mn and Mg Co-Addition
Previous Article in Journal
Effect of Deep Cryogenic Time on the Microstructure and Mechanical Property of Cr-Mn-Si High-Strength Alloy Steel
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Metals
Volume 13
Issue 8
10.3390/met13081450
metals-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Solidification Behavior of Undercooled Fe75B25 Alloy

by
Changsong Ma
,
Lin Yang
and
Jinfu Li
*
State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
*
Author to whom correspondence should be addressed.
Metals 2023, 13(8), 1450; https://doi.org/10.3390/met13081450
Submission received: 24 July 2023 / Revised: 6 August 2023 / Accepted: 7 August 2023 / Published: 11 August 2023
Browse Figures
Versions Notes

Abstract

:
The paper presents a study of the phase selection and microstructure evolution of Fe75B25 alloy subjected to solidification at various undercoolings. The alloy invariably solidifies into a primary Fe2B phase and α-Fe/Fe2B eutectic at all the experimental undercoolings up to 381 K. A metastable Fe3B phase does not precipitate, although its growth in this alloy is favored without large-scale solute diffusion involved. It is shown that the phase selection is nucleation-controlled. Solid sites existing in the alloy melt seem more favorable for the nucleation of the Fe2B phase. As undercooling increases, primary the Fe2B phase changes its morphology complexly. It solidifies into coarse faceted dendrites at low undercoolings, developed non-faceted dendrites at moderate undercoolings, seaweeds with dense branches at higher undercoolings, and refined granular grains at undercooling above 147 K.

1. Introduction

The eternal theme of material science research is to control the microstructure of materials to obtain the required properties [1]. Solidification is a phase transformation process of a substance from liquid to solid and widely exists in the nature and engineering fields. Most metallic materials undergo at least one or multiple solidification processes during preparation, such as casting and welding. Therefore, the control of the solidification process is particularly important for both structural and functional materials [2]. This brought about the invention of advanced solidification technologies such as 3D printing, magnetic field solidification, ultrasonic solidification, etc. According to different cooling rates, solidification can be divided into equilibrium solidification, near-equilibrium solidification, and rapid solidification. Rapid solidification is also known as non-equilibrium solidification due to its particularly fast cooling rate [3]. Solidification of deeply undercooled alloy melts is typically a non-equilibrium process, during which crystals grow rapidly once nucleation takes place [4]. Dependent on the alloy feature and the undercooling degree, a series of interesting phenomena may occur in the solidification microstructure, including metastable phase precipitation [5,6], abnormal eutectic formation [7,8], grain refinement [9,10,11], coupled peritectic growth [12,13], solute trapping [14,15], etc. Correspondingly, the gained alloys possess many unique properties, and the non-equilibrium solidification behavior has thus been attracting much attention in recent decades [16,17].
Metastable phases form because of their lower solid/liquid interfacial energy, which can decrease the nucleation work considerably at high undercooling temperatures and possibly induce faster crystal growth kinetics [18,19,20]. There have been lots of reports on metastable phase formation in undercooled alloy melts. In the solidification of some Co-B and Ni-B alloys, Co23B6 and Ni23B6 metastable phases were detected to form from the cooling curves and microstructural morphology [21,22]. However, the X-ray diffraction (XRD) results did not show any spectrum of these metastable phases, indicating that the initial metastable phase had been decomposed during the subsequent solidification process. Similar situations have also been observed in systems such as Fe-Ni and Fe-Co, where a δ-Fe metastable phase precipitated from the deeply undercooled melt, but any information related to the δ-Fe phase could be found when analyzing the phase constitution of the solidified samples, suggesting that δ-Fe had been remelted [23].
Fe and B elements are present in lots of alloys as the base components, as they can create materials with attractive properties such as magnetic properties, glass-forming ability, mechanical properties, etc. [24,25]. Meanwhile, Fe-B alloys are ideal objects to investigate metastable phase formation. Besides α-Fe, the other possible phases are all intermetallic compounds in Fe-rich Fe-B alloys. They are Fe23B6, Fe3B, Fe2B, and FeB, of which the former two are metastable phases according to the equilibrium phase diagram. In 1982, Kaha et al. [26] first reported the existence of metastable phase Fe3B in rapidly quenched samples. Antonio et al. [27] studied the crystallization behavior of the Fe-Si-B amorphous alloys. They found that the metastable phase Fe3B could precipitate at the composition of 12–25 at.%. B. Battezzati et al. [28] collected the thermal data of Fe-B alloys with different compositions through thermal analysis and determined that the metastable eutectic transformation temperature of L → Fe + Fe3B was 1387 K. Palumbo et al. [29] further used the CALPHAD approach to draw a metastable eutectic phase diagram containing Fe3B.
The Fe3B phase often forms during devitrification of Fe-B-based metallic glasses [30,31,32,33], meaning that this phase may also form in solidification so long as the melt undercooling is large enough. Mizuno et al. [34] studied the solidification behavior of Fe83B17 eutectic alloy under containerless cooling conditions using time-resolved synchrotron X-ray diffraction, and detected the formation of metastable phase Fe23B6 from the undercooled melt as the primary phase. When the cooling rate was lower than 30 K/s, the Fe23B6 phase was decomposed into Fe and Fe2B phases in the subsequent cooling process. But as the cooling rate reached 180 K/s, it would be retained with bcc-Fe. Recently, Quirinale et al. [35] used in situ synchrotron radiation X-ray and electrostatic levitation furnace to study the solidification of undercooled Fe83B17 eutectic alloy and found that either Fe + Fe2B or Fe + Fe23B6 metastable phases precipitated from the undercooled melt, and then Fe23B6 metastable phase was decomposed into Fe and Fe3B phases. Using the glass flux technique, Yang et al. [36] and Zhang et al. [37] undercooled some Fe-B alloys to very high degrees, and successfully obtained Fe3B phase in the room solidification microstructure.
Yang et al. [38] carefully investigated the solidification behavior of the Fe-B alloys around the eutectic composition of Fe83B17. It was found that the Fe3B phase could primarily form as a eutectic phase at large enough undercoolings. Their work, however, also indicates that the critical undercooling for Fe3B phase to form increases with increasing B content. On the other hand, the Fe3B phase gains advantageous growth kinetics as the alloy composition approaches Fe75B25 because its growth in this alloy does not need long-range atomic diffusion. Without further investigations on the Fe-B alloys with more B content, it is unclear whether the Fe3B phase can form as a sole primary phase. To our knowledge, there has been no investigation on the solidification of undercooled Fe75B25 alloy.
Therefore, we solidified Fe75B25 alloy at various undercoolings in this work to explore the phase selection and microstructural evolution. It is also believed that the experimental investigation with Fe75B25 alloy is helpful for clarifying whether the phase selection in Fe-B alloys is controlled by nucleation or growth kinetics.

2. Materials and Experimental Procedures

2.1. Materials

Fe75B25 alloy was synthesized by arc melting a mixture of high-purity Fe (99.999 wt.%) and B (99.999 wt.%) blocks under a high-purity argon atmosphere on a water-cooled copper hearth. Considering that the B element has a high melting point and is prone to burning loss, a master alloy was melted first. By weighing the mass change of the master alloy before and after melting, the B element content of the master alloy was determined. The amount of Fe to be added to the master alloy was calculated based on the target composition. Each Fe75B25 alloy ingot was remelted several times and turned over after each melting operation to ensure chemical homogeneity. The alloy prepared using this method has an accurate composition to ensure the effectiveness of the experiment.

2.2. Experimental Procedures

In the undercooling experiment, about 3 g of the alloy and a small quantity of B2O3 glass flux were put together into a fused silica crucible with 12 mm diameter and inserted in the induction heating coil. After evacuating the vacuum chamber to a pressure of 2 × 10−3 Pa, ultra-high-purity argon was back-filled into the chamber, followed by induction melting of the alloy. The heating speed was controlled by adjusting the current of the induction coil. To prevent the alloy from possible oxidation by the residual oxygen in the chamber, the glass flux was controlled to first melt and hold around 1073 K for a period of time to ensure that the molten glass flux completely enclosed the alloy. Then, the temperature continued to rise above the melting point of the alloy. When the melting point was reached during the heating process, there would be a plateau or turning point on the heating curve. The superheating was controlled within 200–300 K and the melt was held at the highest temperature for a period of time. Then the power of induction was cut off and the melt was cooled spontaneously. An infrared pyrometer with an accuracy of ±1 K and a response time of 1 ms was utilized to monitor the thermal history of the alloy, and the temperature data were recorded in a computer. The alloy was cyclically superheated and cooled until a desired undercooling was obtained. The value of undercooling was determined by subtracting the nucleation temperature on the cooling curve from the plateau temperature on the heating curve [39]. Besides the nucleation temperature, the cooling curve can provide a lot of valuable information, such as recalescence rate [40] and solid fraction [41], etc.
Each solidified sample was sectioned, polished, and etched with a mixture of 3% nitric acid and alcohol. The solidification microstructure was analyzed using an optical microscope (OM, Olympus, Tokyo, Japan) and a scanning electron microscope with the second electron mode (SEM-SE, JSM-7800F, JEOL, Tokyo, Japan). Due to the uneven cooling rate across the sample from the center to the surface, the microstructure at a radius of 1/2 was selected for observation to ensure the representativeness of the analyzed sample. The phase constitution of the alloy was analyzed in a Rigaku SmartLab X-ray diffractometer (XRD, Rigaku, Tokyo, Japan) with monochromatic Co Kα radiation. The parameters of XRD are tube voltage 30 kV, tube current 30 mA, scanning range 30°–90°, scanning speed 2°/min, and scanning step 0.02°. Electron back scatter diffraction (EBSD, Oxford Aztec, UK) measurement was performed to reveal the phase distribution and orientation relationship between crystals with AZtecHKL software (Version 3.2, Oxford AZtec, UK). The EBSD specimens were prepared by rough grinding, fine grinding, and polishing. They then underwent surface stress relief treatment by electropolishing. The electrolyte for electropolishing was 10% perchloric acid alcohol solution, the polishing voltage was 30 V, the polishing current was 1 A, and the polishing time was 10–30 s. The EBSD scanning step depended on the grain size, smaller than 1/10 of the grain size. The microstructure was further analyzed in a transmission electron microscope (TEM, FEI Talos F200X, Waltham, MA, USA). The TEM specimen with an initial thickness of about 300 μm was cut from the solidified sample by electrical discharging. It was then thinned to 30 μm using focused ion beam (FIB) technology.

3. Results

3.1. XRD Patterns

Defining the melt undercooling, ΔT, as the difference between Tl (the equilibrium liquidus temperature) and initial nucleation temperature, the maximum undercooling achieved in the experiment with Fe75B25 alloy was 381 K. XRD patterns of the alloy solidified at different undercoolings are shown in Figure 1. The alloy constantly solidifies into α-Fe and Fe2B phases no matter how high the undercooling is. Neither Fe3B nor Fe23B6 metastable phases exist even at the largest undercooling of 381 K. It is clear that an alloy far from the eutectic composition (Fe83B17) but around the nominal composition of the Fe3B phase (Fe75B25) cannot also solidify with the Fe3B phase.

3.2. Cooling Curves

According to the equilibrium phase diagram, Fe2B should firstly precipitate as a primary phase when the Fe75B25 melt is cooled below the liquidus temperature that has been experimentally determined to be about 1616 K. As temperature further drops to 1448 K (the eutectic temperature of α-Fe and Fe2B, TE), the residual liquid solidifies into α-Fe/Fe2B eutectic through a eutectic reaction. Figure 2 shows the cooling curves. It can be seen that the cooling curves can be divided into three types. The first type occurs with undercooling less than 147 K, where the first recalescence event corresponding to primary Fe2B formation takes place above TE, while the second one always takes place below the initial nucleation temperature. The second type appears with 183 K and 239 K undercoolings. Although there are still two recalescence events in this case, the initial nucleation temperature is below TE, while the second recalescence event also remains. The third type of cooling curve appears with undercoolings above 293 K. Now there is only one recalescence event; the nucleation temperature is below TE, and there exists a plateau on the curve after the recalescence, as shown by the insert in Figure 2.

3.3. Microstructures

Figure 3 shows the sectional microstructure of Fe75B25 alloy samples solidified at different undercoolings. The solidification microstructure consists of coarse dendrites of a primary Fe2B phase and inter-dendritic eutectic at low ΔT (Figure 3a). The primary Fe2B phase shows obvious faceted features: hollow crystals with sharp surfaces. As ΔT increases, the faceted feature of the primary Fe2B phase is degenerated and the dendrite arms become thinner (Figure 3b). At larger undercoolings, for example, at 129 K, dendrites branching along special crystal orientations disappear from the microstructure. Instead, seaweeds of primary Fe2B phase with dense branches form (Figure 3c). Continuously increasing undercooling brings about the breaking of the branches, as shown in Figure 3d. The break-up of the branches becomes more and more severe as the undercooling increases, indicated by an increasing fraction of granular grains of primary Fe2B phase. From Figure 3e it can be seen that the primary Fe2B phase has been composed of full granular grains at an undercooling of 366 K. Between them are distributed α-Fe/Fe2B eutectics. At the largest experimental undercooling of 381 K, the grains of the Fe2B phase become finer (Figure 3f).

3.4. SEM and EBSD Analyses

Typical samples solidified at an undercooling of 73 K, 147 K, and 366 K, respectively, were analyzed in SEM and EBSD. Figure 4 shows some SEM-SE micrographs, with EBSD phase color maps inserted. It can be seen that the primary phase is indeed Fe2B, and α-Fe/Fe2B eutectic distributes between the primary Fe2B phase.
Crystal orientations in the samples were further analyzed using EBSD. Figure 5 shows the Euler maps and pole figures. At undercooling of 73 K, both α-Fe and Fe2B phases are oriented and their overlapping pole points demonstrate specific orientation relationships between (110) α-Fe and (001) Fe2B (marked in white circles in the figure). This is not surprising. Dendrites grow through branching along special crystal directions, determining that all the branches within the Fe2B dendritic crystal are well-oriented. α-Fe/Fe2B eutectic solidifies from the residual liquid. The eutectic Fe2B phase epitaxially grows from the primary Fe2B phase; thus, they have the same orientation in the microstructure. To minimize the free energy, two eutectic phases grow with special crystal planes coupled. For the alloy solidified at 147 K undercooling where a large-scale break-up of the seaweed branches has taken place, the pole points in the pole figure are randomly distributed, indicating that α-Fe and Fe2B are completely randomly distributed. When the undercooling increases to 366 K, the pole points of α-Fe in the pole figure are randomly distributed, but the pole points of Fe2B have a certain orientation compared with those at 147 K undercooling.

4. Discussion

4.1. Phase Selection

A metastable phase forms because it is superior to the stable phase in nucleation or growth kinetics. The present investigation clearly reveals that Fe3B metastable phase cannot gain any advantage to form in Fe75B25 alloy even though its growth in this alloy does not need any long-range solute diffusion. Therefore, the phase selection in the solidification of Fe75B25 alloy should be controlled by the nucleation step. Figure 6 shows the critical homogeneous nucleation work of Fe3B and Fe2B at various undercoolings in Fe75B25 alloy. The physical parameters used for calculation are listed in Table 1. Two curves intersect at an undercooling of 270 K, above which the critical nucleation work of Fe3B is smaller than that of the Fe2B phase, meaning that the Fe3B phase should preferentially form if the solidification proceeds through homogeneous nucleation. But the fact is that there is only Fe2B as the primary phase throughout the whole experimental undercooling range. A possible reason is that there were foreign substrates involved in the phase selection, i.e., the solid sites in the alloy melt are better nucleating agents for the Fe2B phase, which inhibits the nucleation of Fe3B.
After several decades of studies, it has been widely accepted that heterogeneous nucleation dominates the actual solidification of undercooled alloy melts since the melt undercoolings achieved are far smaller than the undercoolings for homogeneous nucleation. In investigating the solidification of undercooled Ni-Cu alloys, Willnecker et al. [42] found that the nucleation behavior in the alloys could be well-described by setting the catalytic potency factor  f ( θ ) =  0.19. They further argued that there were solid sites in the melts that inevitably triggered heterogeneous nucleation. The catalytic potency of a substrate is different for different phases. Obviously, the catalytic potency factor of existing substrates in the present alloy for the Fe2B phase is far smaller than that for the Fe3B phase, which elevates the intersection of the heterogeneous nucleation work curves of two phases to an undercooling beyond the largest experimental undercooling (381 K). He et al. [43,44] found that a strong magnetic field can affect the catalytic potency factors of Co23B6 and Co3B, leading to the precipitation of Co23B6 metastable phases from undercooled melts and inhibiting the decomposition of the metastable phases. Thus, if the effective nucleating agents for the Fe2B phase can be eliminated or removed, the Fe3B phase may form preferentially at large undercooling.
In the solidification of undercooled Fe-B binary alloys, Yang et al. [36] found that the alloys around the eutectic composition (Fe83B17) solidified into α-Fe/Fe3B eutectic when the undercooling was larger than 400 K, but the alloys with more B content solidified without Fe3B phase. As mentioned above, the phase selection in Fe-B alloys is controlled by nucleation. From the phase diagram it is known that the interval between the liquidus temperatures of Fe2B and Fe3B enlarges with increasing B content, which reduces the effective undercooling for Fe3B to nucleate at a given melt undercooling, and correspondingly is adverse to the formation of Fe3B phase.
A change in primary phase surely influences the crystal growth velocity. Examining the relationship between growth velocity and undercooling can often provide valuable clues to the phase selection. Crystal growth velocity is proportional to recalescence rate [40], i.e., the ratio between the recalescence degree (the difference between the nucleation temperature and maximum recalescence temperature) and recalescence time. Thus, if phase selection took place in the solidification of undercooled Fe75B25 alloy, it would reflect on the curve of recalescence rate versus undercooling. Figure 7 shows the recalescence rate in the first recalescence event. As undercooling increases, the recalescence rate increases almost linearly. There is no breakpoint or inflection point on the curve, meaning that the primary solid remains unchanged, i.e., only the Fe2B primary phase, no other phases, forms in the solidification.

4.2. Microstructural Evolution

Fe75B25 alloy constantly solidifies into Fe2B primary phase and α-Fe/Fe2B eutectic at all undercoolings. However, the morphology of the Fe2B primary phase varies with undercooling significantly. As an intermetallic compound, the Fe2B phase is essentially faceted. But its Jackson’s factor ∆Sf/R = 1.94 (∆Sf is the entropy of fusion and R is the gas constant) is very near the critical value of 2 to distinguish faceted and non-faceted solid/liquid interfaces [45]. As a result, a slight increase in undercooling makes the solidification interface change from faceted to non-faceted morphology.
Solidification interfaces branch in dendritic or seaweed mode, depending on the interface energy anisotropy strength and growth kinetics [46]. A higher interface energy anisotropy strength or lower interface kinetics is favorable for the appearance of dendritic structure. Otherwise, a seaweed structure is favored [47]. Influenced by the rapid interfacial kinetics, the Fe2B phase grows into a seaweed structure as the undercooling of the Fe75B25 melt is larger than 100 K (see Figure 3c).
As we all know, solute diffusion influences crystal growth significantly [48,49]. Fe2B is a stoichiometric compound, meaning that its solidification seldom involves solute trapping, i.e., it cannot be supersaturated with the solute. Chemical superheating of a primary solid, which is widely thought to be the main reason for grain refinement in many alloys, is unavailable in the solidification of Fe75B25 alloy [6]. Grain refinement can also occur through the solidification stress-induced recrystallization [50]. This mechanism may play a role in the solidification of undercooled Fe75B25 alloy. To clarify this point, the microstructure of the sample solidified at undercooling of 147 K was observed by TEM. A few surviving un-recrystallized Fe2B grains were detected, as shown in Figure 8. Dense stacking faults exist in the original Fe2B grains, verified by clusters of the diffraction spots in the selected area diffraction (SAD) pattern. Under the action of these crystal defects, recrystallization took place in the rapidly solidified Fe2B seaweeds [51], resulting in the grain refinement at large undercooling.

5. Conclusions

To clarify the mechanism underlying the phase selection in the Fe-B system, Fe75B25 alloy was solidified at undercoolings up to 381 K. The following conclusions are reached:
(1) Fe75B25 alloy invariably solidifies into a primary Fe2B phase and α-Fe/Fe2B eutectic at all the experimental undercoolings. No metastable phases including Fe3B are involved in the solidification, meaning that the Fe3B phase does not gain any advantage to form in Fe75B25 alloy, although its growth in this alloy does not need any solute diffusion.
(2) The phase selection in undercooled Fe75B25 alloy is controlled by heterogeneous nucleation. The solid sites existing in the alloy melt are more favorable for the nucleation of the Fe2B phase. As undercooling increases, the morphology of the primary Fe2B phase varies complexly.

Author Contributions

Methodology, L.Y.; Validation, J.L.; Formal analysis, L.Y.; Investigation, C.M. and L.Y.; Resources, J.L.; Data curation, C.M.; Writing—original draft, C.M.; Writing—review and editing, J.L.; Supervision, J.L.; Project administration, J.L.; Funding acquisition, J.L. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (Grant Nos. 51771116, 52231002, 51620105012 and 51821001).

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Kurz, W.; Rappaz, M.; Trivedi, R. Progress in modelling solidification microstructures in metals and alloys. Part II: Dendrites from 2001 to 2018. Int. Mater. Rev. 2021, 66, 30–76. [Google Scholar] [CrossRef]
  2. Sun, C.C. Materials science tetrahedron-A useful tool for pharmaceutical research and development. J. Pharm. Sci. 2009, 98, 1671–1687. [Google Scholar] [CrossRef]
  3. Herlach, D.M. Non-equilibrium solidification of undercooled metallic melts. Metals 2014, 4, 196–234. [Google Scholar] [CrossRef] [Green Version]
  4. Herlach, D.M. Solidification from undercooled melts. Mater. Sci. Eng. A 1997, 226–228, 348–356. [Google Scholar] [CrossRef]
  5. Zhang, B.W.; Hong, Z.Y.; Zhao, H.L.; Yan, N.; Hu, L. Microstructure, precipitation behavior, and properties of quaternary Cu–Be–Co–Ni alloy under electromagnetic levitation. Mater. Sci. Eng. A 2023, 868, 144774. [Google Scholar] [CrossRef]
  6. Li, J.F.; Zhou, Y.H. Remelting of primary solid in rapid solidification of deeply undercooled alloy melts. Acta Metall. Sin. 2018, 54, 627–636. [Google Scholar]
  7. Ao, X.H.; Xia, H.X.; Liu, J.H.; He, Q.Y.; Lin, S.X. A numerical study of irregular eutectic in Al-Si alloys under a large undercooling. Comp. Mater. Sci. 2021, 186, 110049. [Google Scholar] [CrossRef]
  8. Li, W.; Wei, X.X.; Li, J.F. Anomalous eutectic formation in undercooled Ni-P eutectic alloy. T. Nonferr. Metal. Soc. 2023, 33, 507–517. [Google Scholar] [CrossRef]
  9. Li, S.J.; Cui, D.X.; Zhang, J.B.; Li, X.; Qu, J.R.; Zhang, P.F.; Wang, H.F. Microstructure evolution and grain refinement mechanism in undercooled (CoFe)50Si50 multi-principal element intermetallics. Mater. Charact. 2023, 204, 113184. [Google Scholar] [CrossRef]
  10. Mullis, A.M. The origins of spontaneous grain refinement in deeply undercooled metallic melts. Metals 2014, 4, 155–167. [Google Scholar] [CrossRef] [Green Version]
  11. Xu, X.L.; Hao, Y.C.; Dong, R.F.; Hou, H.; Zhao, Y.H. Effect of undercooling on microstructure evolution of Cu based alloys. J. Alloys Compd. 2023, 935, 167998. [Google Scholar] [CrossRef]
  12. Kerr, H.W.; Kurz, W. Solidification of peritectic alloys. Int. Mater. Rev. 1996, 41, 129–164. [Google Scholar] [CrossRef]
  13. Sha, S.; Chang, J.; Xu, S.S.; Wei, B. Metastable coupled growth kinetics between primary and peritectic intermetallic compounds within the liquid Mo-37 wt% Co refractory alloy. J. Alloys Compd. 2022, 921, 166168. [Google Scholar] [CrossRef]
  14. Pinomaa, T.; Laukkanen, A.; Provatas, N. Solute trapping in rapid solidification. MRS Bull. 2020, 45, 910–915. [Google Scholar] [CrossRef]
  15. Xu, X.L.; Hao, Y.C.; Wu, Q.; Dong, R.F.; Wu, L.; Zhao, Y.H. Effect of minor addition of Co on nonequilibrium solidification of deeply undercooled Cu based alloys. Mater. Charact. 2023, 199, 112800. [Google Scholar] [CrossRef]
  16. Sunbul, S.E.; Akyol, S.; Onal, S.; Ozturk, S.; Sozeri, H.; Icin, K. Effect of Co, Cu, and Mo alloying metals on electrochemical and magnetic properties of Fe-B alloy. J. Alloys Compd. 2003, 947, 169652. [Google Scholar] [CrossRef]
  17. Herlach, D.M.; Gao, J.; Holland-Moritz, D.; Volkmann, T. Nucleation and phase-selection in undercooled melts. Mater. Sci. Eng. A 2004, 375–377, 9–15. [Google Scholar] [CrossRef]
  18. Herlach, D.M. Non-equilibrium solidification of undercooled metallic metls. Mater. Sci. Eng. R. 1994, 12, 177–272. [Google Scholar] [CrossRef]
  19. Li, M.; Ozawa, S.; Kuribayashi, K. On determining the phase-selection principle in solidification from undercooled melts-competitive nucleation or competitive growth? Phil. Mag. Lett. 2004, 84, 483–493. [Google Scholar] [CrossRef]
  20. Perepezko, J.H. Nucleation reactions in undercooled liquids. Mater. Sci. Eng. 1984, 65, 125–135. [Google Scholar] [CrossRef]
  21. Liu, L.J.; Yang, L.; Li, J.F. Solidification pathways in highly undercooled Co79.3B20.7 alloy. Metall. Mater. Trans. A 2021, 52, 4324–4330. [Google Scholar] [CrossRef]
  22. Liu, F.; Xu, J.F.; Zhang, D.; Jian, Z.Y. Solidification of highly undercooled hypereutectic Ni-Ni3B alloy melt. Metall. Mater. Trans. A 2014, 45, 4810–4819. [Google Scholar] [CrossRef]
  23. Li, M.J.; Yang, G.C.; Zhou, Y.H. Dendrite morphologies of the metastable phase fromundercooled Fe-30at% Co melts and its stabilities. J. Mater. Sci. 2000, 35, 3069–3075. [Google Scholar]
  24. Zhao, X.B.; Li, L.; Bao, K.; Zhu, P.W.; Tao, Q.; Ma, S.L.; Liu, B.; Ge, Y.F.; Li, D.; Cui, T. Synthesis and characterization of a strong ferromagnetic and high hardness intermetallic compound Fe2B. Phys. Chem. Chem. Phys. 2020, 22, 27425–27432. [Google Scholar] [CrossRef] [PubMed]
  25. Hui, L.L.; Xie, Z.X.; Li, C.M.; Chen, Z.Q. Fe-X (X=B, N) binary compounds: First-principles calculations of electronic structures, theoretic hardness and magnetic properties. J. Magn. Magn. Mater. 2018, 451, 761–769. [Google Scholar] [CrossRef]
  26. Khan, Y.; Kneller, E.; Sostarich, M. The Iron-Boron (Fe3B) Phase. Z. Metallkde 1982, 73, 624–626. [Google Scholar]
  27. Antonione, C.; Battezzati, L.; Cocco, G.; Marino, F. Thermochemical and Structural Investigation of Crystallization in Fe-B and Fe-Si-B Metallic Glasses. Z. Metallkde 1984, 75, 714. [Google Scholar] [CrossRef]
  28. Baricco, M.; Battezzati, L.; Antonione, C. Undercooling of Ni-B and Fe-B alloys and their metastable phase diagrams. J. Alloys Compd. 1997, 247, 164–171. [Google Scholar]
  29. Palumbo, M.; Cacciamani, G.; Bosco, E.; Baricco, M. Driving forces for crystal nucleation in Fe-B liquid and amorphous alloys. Intermetallics 2003, 11, 1293–1299. [Google Scholar] [CrossRef]
  30. Kim, W.; Duan, T.R.; Perepezko, J.H. Nanocrystal evolution during ultra-fast heating in an amorphous Fe85B15 alloy. Scripta Mater. 2023, 225, 115155. [Google Scholar] [CrossRef]
  31. Lu, S.H.; Wang, M.G.; Zhao, Z.K. Recent advances and future developments in Fe-based amorphous soft magnetic composites. J. Noncryst. Solids 2023, 616, 122440. [Google Scholar] [CrossRef]
  32. Konstantinidis, N.; Fos, A.; Svec, P.N.; Vourna, P.; Hristoforo, E. Morphology and magnetic properties of rapidly quenched Fe-B alloys. J. Magn. Magn. Mater. 2022, 564, 170054. [Google Scholar] [CrossRef]
  33. Chu, F.; Jian, X.Y.; Edalati, K.; Yan, Y.Q.; Ke, H.B.; Zhang, P.; Lin, H.J. Nanoscale heterogeneous FeB metallic glass as highly active and stable catalyst for hydrogen evolution. J. Alloys Compd. 2023, 960, 170964. [Google Scholar] [CrossRef]
  34. Mizuno, A.; Tamura, J.; Kohara, S.; Watanabe, M. Time-resolved X-ray diffraction study on solidification of Fe-B and Fe-C eutectic alloys. Mater. Sci. Forum 2012, 706, 1702–1706. [Google Scholar] [CrossRef]
  35. Quirinale, D.G.; Messina, D.; Rustan, G.E.; Kreyssig, A.; Prozorov, R.; Goldman, A.I. In situ investigation of magnetism in metastable phases of levitated Fe83B17 during solidification. Phys. Rev. Appl. 2017, 8, 054046. [Google Scholar] [CrossRef]
  36. Yang, C.L.; Liu, F.; Yang, G.C.; Chen, Y.Z.; Liu, N.; Zhou, Y.H. Microstructure and phase selection in bulk undercooled Fe–B eutectic alloys. J. Alloys Compd. 2007, 441, 101–106. [Google Scholar] [CrossRef]
  37. Zhang, D.; Xu, J.F.; Liu, F. In situ observation of the competition between metastable and stable phases in solidification of undercooled Fe-17 at. pct B alloy melt. Metall. Mater. Trans. A 2015, 46, 5232–5239. [Google Scholar] [CrossRef]
  38. Yang, C.L.; Liu, F.; Yang, G.C.; Zhou, Y.H. Structure evolution upon non-equilibrium solidification of bulk undercooled Fe–B system. J. Cryst. Growth 2009, 311, 404–412. [Google Scholar] [CrossRef]
  39. Li, Y.; Liu, L.J.; Li, X.; Li, J.F. Solidification of Undercooled Co75B25 Alloy. Acta Metall. Sin. 2018, 54, 1165–1170. [Google Scholar]
  40. Xu, J.F.; Yang, T.; Li, Z.; Wang, X.; Xiao, Y.; Jian, Z.Y. The recalescence rate of cooling curve for undercooled solidification. Sci. Rep. 2020, 10, 1380. [Google Scholar] [CrossRef] [Green Version]
  41. Xu, J.F.; Liu, F.; Xu, X.L.; Chen, Y.Z. Determination of solid fraction from cooling curve. Metall. Mater. Trans. A 2012, 43, 1268–1276. [Google Scholar] [CrossRef]
  42. Willnecker, R.; Herlach, D.M.; Feuerbacher, B. Nucleation in bulk undercooled nickel-base alloys. Mater. Sci. Eng. 1988, 98, 85–88. [Google Scholar] [CrossRef]
  43. He, Y.X.; Wu, Y.H.; Bu, F.; Zou, C.X.; Bian, Z.C.; Huang, Q.L.; Wang, T.; Wang, J.; Li, J.S.; Beaugnon, E. Effects of an ultra-high magnetic field up to 25 T on the phase transformations of undercooled Co-B eutectic alloy. J. Mater. Sci. Technol. 2021, 93, 79–88. [Google Scholar] [CrossRef]
  44. He, Y.X.; Li, J.S.; Li, L.Y.; Wang, J.; Yildiz, E.; Beaugnon, E. Magnetic-field-induced chain-like assemblies of the primary phase during non-equilibrium solidification of a Co-B eutectic alloy: Experiments and modeling. J. Alloys Compd. 2020, 815, 152446. [Google Scholar] [CrossRef]
  45. Jackson, K.A.; Uhlmann, D.R.; Hunt, J.D. On the nature of crystal growth from the melt. J. Cryst. Growth 1974, 24–25, 130–137. [Google Scholar] [CrossRef]
  46. Herlach, D.M. Dendrite Growth kinetics in undercooled melts of intermetallic compounds. Crystals 2015, 5, 355–375. [Google Scholar] [CrossRef] [Green Version]
  47. Liu, S.K.; Guo, C.W.; Fan, Y.H.; Dong, X.L.; Zhao, H.L.; Xing, H.; Lu, Y.L. A phase-field study of the pattern selection between dendrite and seaweed during directional solidification. Comp. Mater. Sci. 2022, 203, 111171. [Google Scholar] [CrossRef]
  48. Kuang, W.W.; Wang, H.F.; Li, X.; Zhang, J.B.; Zhou, Q.; Zhao, Y.H. Application of the thermodynamic extremal principle to diffusion-controlled phase transformations in Fe-C-X alloys: Modeling and applications. Acta Mater. 2018, 159, 16–30. [Google Scholar] [CrossRef]
  49. Zhao, Y.H.; Zhang, B.; Hou, H.; Chen, W.P.; Wang, M. Phase-field simulation for the evolution of solid/liquid interface front in directional solidification process. J. Mater. Sci. Technol. 2019, 35, 1044–1052. [Google Scholar] [CrossRef]
  50. An, Y.K.; Liang, L.; Xu, X.L.; Zhao, Y.H.; Hou, H. Effect of bulk undercooling on microstructure transformation mechanism of rapidly solidified Nickel alloys. J. Mater. Sci. Technol. 2021, 11, 548–563. [Google Scholar] [CrossRef]
  51. Bu, F.; Zhang, Y.Y.; Liu, H.X.; Wang, J.; Beaugnon, E.; Li, J.S.; He, Y.X. Magnetic field intensity dependent microstructure evolution and recrystallization behavior in a Co-B eutectic alloy. J. Mater. Sci. Technol. 2023, 138, 93–107. [Google Scholar] [CrossRef]
Metals 13 01450 g001
Figure 1. XRD patterns of Fe75B25 alloy solidified at different undercoolings.
Figure 1. XRD patterns of Fe75B25 alloy solidified at different undercoolings.
Metals 13 01450 g001
Metals 13 01450 g002
Figure 2. Cooling curves of Fe75B25 alloy at different undercoolings (Tl is the equilibrium liquidus temperature and TE is the eutectic temperature).
Figure 2. Cooling curves of Fe75B25 alloy at different undercoolings (Tl is the equilibrium liquidus temperature and TE is the eutectic temperature).
Metals 13 01450 g002
Metals 13 01450 g003
Figure 3. OM images of the sectional microstructure of Fe75B25 alloy at undercooling of (a) 38 K, (b) 73 K, (c) 129 K, (d) 147 K, (e) 366 K, (f) 381 K. Inserts are the local magnifications.
Figure 3. OM images of the sectional microstructure of Fe75B25 alloy at undercooling of (a) 38 K, (b) 73 K, (c) 129 K, (d) 147 K, (e) 366 K, (f) 381 K. Inserts are the local magnifications.
Metals 13 01450 g003
Metals 13 01450 g004
Figure 4. SEM-SE micrographs of Fe75B25 alloy at undercooling of (a) 73 K, (b) 147 K, and (c) 366 K. Inserts are the corresponding EBSD phase color map.
Figure 4. SEM-SE micrographs of Fe75B25 alloy at undercooling of (a) 73 K, (b) 147 K, and (c) 366 K. Inserts are the corresponding EBSD phase color map.
Metals 13 01450 g004
Metals 13 01450 g005
Figure 5. EBSD Euler maps and pole figures indexed to α-Fe and Fe2B phase in Fe75B25 alloy when (a) ΔT = 73 K, (b) ΔT = 147 K, (c) ΔT = 366 K.
Figure 5. EBSD Euler maps and pole figures indexed to α-Fe and Fe2B phase in Fe75B25 alloy when (a) ΔT = 73 K, (b) ΔT = 147 K, (c) ΔT = 366 K.
Metals 13 01450 g005
Metals 13 01450 g006
Figure 6. Critical homogeneous nucleation work of Fe3B and Fe2B phases at various undercoolings.
Figure 6. Critical homogeneous nucleation work of Fe3B and Fe2B phases at various undercoolings.
Metals 13 01450 g006
Metals 13 01450 g007
Figure 7. Relationship between the first recalescence rate and undercooling.
Figure 7. Relationship between the first recalescence rate and undercooling.
Metals 13 01450 g007
Metals 13 01450 g008
Figure 8. TEM analysis of the sample solidified at undercooling of 147 K: (a) bright-field image, (b) SAD pattern of the marked region in (a).
Figure 8. TEM analysis of the sample solidified at undercooling of 147 K: (a) bright-field image, (b) SAD pattern of the marked region in (a).
Metals 13 01450 g008
Table 1. Physical parameters used for calculating the critical work of nucleation for various phases in Fe75B25 alloy [29,37].
Table 1. Physical parameters used for calculating the critical work of nucleation for various phases in Fe75B25 alloy [29,37].
PropertySymbolFe3BFe2B
Melting temperatureTm (K)14311671
Mole volumeVm × 10−6 (m3·mol−1)6.0945.533
Latent heat of fusionΔH (kJ·mol−1)18.1126.89
Structural factorα0.220.44
Liquidus temperatureTl (K)16161616
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Ma, C.; Yang, L.; Li, J. Solidification Behavior of Undercooled Fe75B25 Alloy. Metals 2023, 13, 1450. https://doi.org/10.3390/met13081450

AMA Style

Ma C, Yang L, Li J. Solidification Behavior of Undercooled Fe75B25 Alloy. Metals. 2023; 13(8):1450. https://doi.org/10.3390/met13081450

Chicago/Turabian Style

Ma, Changsong, Lin Yang, and Jinfu Li. 2023. "Solidification Behavior of Undercooled Fe75B25 Alloy" Metals 13, no. 8: 1450. https://doi.org/10.3390/met13081450

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop