Solidification of Undercooled (Fe1 -x Co x)79.3B20.7 Alloys
YANG Lin1, MA Changsong1, LIU Lianjie1,2, LI Jinfu1,3()
1 State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China 2 Institute of Materials, China Academy of Engineering Physics, Mianyang 621907, China 3 Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Cite this article:
YANG Lin, MA Changsong, LIU Lianjie, LI Jinfu. Solidification of Undercooled (Fe1 -x Co x)79.3B20.7 Alloys. Acta Metall Sin, 2025, 61(1): 99-108.
M-B (M = Fe, Co, Ni) alloys have garnered significant attention in the automotive, petrochemical, and power electronics industries owing to their excellent corrosion resistance, wear resistance, and high-temperature strength. The service performances of the M-B alloys are closely related to that of borides. Among them, M23B6 generally exists as a metastable phase. However, the understanding of its formation is limited compared to that of other borides. To reveal the effect of Fe/Co content ratio on the solidification behavior of the Fe-Co-B alloys, particularly the formation of M23B6 phase, alloys with nominal composition of (Fe1 - x Co x)79.3B20.7 (x = 0-1) were undercooled using the melt fluxing technique. Consequently, the solidification behaviors were systematically investigated. With the increase in the Co content, the stable eutectic reaction changed from L→α-M + M2B for x <0.4 to L→α-M + M3B for x >0.4. Consequently, the two eutectic reactions occurred at the same temperature at x =0.4, and a peritectic reaction L + M2B→M3B was observed at x > 0.4. With the increase in the undercooling, the primary phase changes from M2B and M23B6 to α-M/M3B in the alloys with x ≤0.6, and from M3B, M2B, and M23B6 to α-M/M3B in the alloys with x >0.6. The increase in Co content reduced the critical undercooling for the M23B6 phase to precipitate primarily and improved its stability, that is, the primary M23B6 phase decomposed into α-M/M2B in the following cooling process when the Co content is not excessively high. However, it could sometimes be reserved to room temperature in case of a very large Co content.
Fig.1 Fe-B and Co-B phase diagrams (a, b), XRD spectra of (Fe1 - x Co x)79.3B20.7 alloy ingots (c), and differential scanning calorimetry (DSC) curve of (Fe1 - x Co x)79.3B20.7 alloys (d) (Black arrows in Fig.1d represents starting or ending tempera-tures of melting process, TE,i/j represents the temperature of the eutectic reaction whose products are i and j)
Fig.2 OM images of (Fe1 - x Co x)79.3B20.7 alloy ingots (Inset in Fig.2d shows the higher magnification microstructure) (a) x = 0 (b) x = 0.2 (c) x = 0.4 (d) x = 0.6 (e) x = 0.8 (f) x = 1.0
Fig.3 Cooling curves (a), XRD spectra (b), and OM images (c-f) of (Fe0.8Co0.2)79.3B20.7 alloy under different undercoolings (ΔT) (Insets in Figs.3d-f show the higher magnification microstructures, TL is the liquidus temperature of the alloy, is the temperature of the eutectic reaction L→α-M + M2B, and is the melting temperature of M23B6 phase) (c) ΔT = 10 K (d) ΔT = 233 K (e) ΔT = 305 K (f) ΔT = 351 K
Fig.4 Cooling curves (a), XRD spectra (b), and OM images (c-f) of (Fe0.6Co0.4)79.3B20.7 alloy under different undercoolings (Insets in Figs.4c-f are magnified views of the areas indicated by the white rectangles) (c) ΔT = 44 K (d) ΔT = 162 K (e) ΔT = 326 K (f) ΔT = 369 K
Fig.5 Microstructures of (Fe0.6Co0.4)79.3B20.7 alloy undercooled by 44 K (a) SEM image (b) EBSD phase map (c) magnified view of the area marked by the white rectangle in Fig.5b
Fig.6 Cooling curves (a), XRD spectra (b), and microstructures (c-f) of (Fe0.4Co0.6)79.3B20.7 alloy under different undercoolings (Inset in Fig.6c is EBSD phase distribution map, and the other insets show the higher magnification images) (c) ΔT = 39 K (d) ΔT = 136 K (e) ΔT = 297 K (f) ΔT = 321 K
Fig.7 Cooling curves (a), XRD spectra (b), and OM images (c-f) of (Fe0.2Co0.8)79.3B20.7 alloy under different undercoolings (Inset in Fig.7c is EBSD phase distribution map, and the other insets show higher magnification OM images) (c) ΔT = 20 K (d) ΔT = 126 K (e) ΔT = 255 K (f) ΔT = 340 K
Fig.8 Schematics of (Fe1 - x Co x)-B pseudo-binary phase diagrams (Solid lines represent stable phase diagrams, dashed lines represent metastable phase diagrams, TE,i + j represents the temperature of the eutectic reaction whose products are i and j) (a) x = 0.4 (b) x = 0.6
Fig.9 Undercooling ranges for various primary phases to precipitate and their dependences on the Co content in (Fe1 - x Co x)79.3B20.7 alloys (, , and represent the critical undercoolings above which M2B, M23B6, and α-M/M3B precipitate as primary phases, respectively)
Fig.10 Schematic of solidification paths for various alloys under different undercoolings
1
Zhang J J, Liu J C, Liao H M, et al. A review on relationship between morphology of boride of Fe-B alloys and the wear/corrosion resistant properties and mechanisms[J]. J. Mater. Res. Technol., 2019, 8: 6308
2
Liu Z W, Zhou B, Liao X F, et al. Research status and future development of (Ce, La, Y)-F-B permanent magnets based on full high-abundance rare earth elements[J]. Acta Metall. Sin., 2024, 60: 585
Ünal E, Yaşar A, Karahan İ H. A review of electrodeposited composite coatings with Ni-B alloy matrix[J]. Mater. Res. Express, 2019, 6: 092004
4
Liu Z W, He J Y. Several issues on the development of grain boundary diffusion process for Nd-Fe-B permanent magnets[J]. Acta Metall. Sin., 2021, 57: 1155
Barati Q, Hadavi S M M. Electroless Ni-B and composite coatings: A critical review on formation mechanism, properties, applications and future trends[J]. Surf. Interfaces, 2020, 21: 100702
6
Xu X L, Hao Y C, Wu Q, et al. Microstructure refinement mechanisms in undercooled solidification of binary and ternary nickel based alloys[J]. J. Mater. Res. Technol., 2023, 24: 737
7
Madah F, Amadeh A A, Dehghanian C. Investigation on the phase transformation of electroless Ni-B coating after dry sliding against alumina ball[J]. J. Alloys Compd., 2016, 658: 272
8
Pal S, Jayaram V. Effect of microstructure on the hardness and dry sliding behavior of electroless Ni-B coating[J]. Materialia, 2018, 4: 47
9
Safavi M S, Tanhaei M, Ahmadipour M F, et al. Electrodeposited Ni-Co alloy-particle composite coatings: A comprehensive review[J]. Surf. Coat. Technol., 2020, 382: 125153
10
Li J F, Zhou Y H. Remelting of primary solid in rapid solidification of deeply undercooled alloy melts[J]. Acta Metall. Sin., 2018, 54: 627
doi: 10.11900/0412.1961.2017.00537
Liang L, Xu X L, Zhao Y H, et al. Solidification microstructure evolution and grain refinement mechanism under high undercooling of undercooled Ni90Cu10 alloys[J]. Mater. Res. Express, 2019, 6(12): 1265k5
12
Li J F, Lü Y L, Yang G C, et al. Secondary arm spacing of undercooled Ni50Cu50 alloy[J]. Acta Metall. Sin., 1998, 34: 586
Quirinale D G, Rustan G E, Kreyssig A, et al. Synergistic stabilization of metastable Fe23B6 and γ-Fe in undercooled Fe83B17 [J]. Appl. Phys. Lett., 2015, 106: 241906
14
Liu L J, Yang L, Li J F. Solidification pathways in highly undercooled Co79.3B20.7 alloy[J]. Metall. Mater. Trans., 2021, 52A: 4324
15
Wei X X, Xu W, Kang J L, et al. Metastable Co23B6 phase solidified from deeply undercooled Co79.3B20.7 alloy melt[J]. J. Mater. Sci., 2016, 51: 6436
16
Xu J F, Liu F, Dang B. Phase selection in undercooled Ni-3.3 wt pct B alloy melt[J]. Metall. Mater. Trans., 2013, 44A: 1401
17
Liu F, Xu J F, Zhang D, et al. Solidification of highly undercooled hypereutectic Ni-Ni3B alloy melt[J]. Metall. Mater. Trans., 2014, 45A: 4810
18
Battezzati L, Antonione C, Baricco M. Undercooling of Ni-B and Fe-B alloys and their metastable phase diagrams[J]. J. Alloys Compd., 1997, 247: 164
19
Ohodnicki Jr P R, Cates N C, Laughlin D E, et al. Ab initio theoretical study of magnetization and phase stability of the (Fe, Co, Ni)23B6 and (Fe, Co, Ni)23Zr6 structures of Cr23C6 and Mn23Th6 prototypes[J]. Phys. Rev., 2008, 78B: 144414
20
Li J F, Li W. Structure and glass-forming ability of Al-based amorphous alloys[J]. Acta Metall. Sin., 2022, 58: 457
doi: 10.11900/0412.1961.2021.00561
Yang G, Liu W G, Han X B, et al. Effects of alloying substitutions on the anti-disproportionation behavior of ZrCo alloy[J]. Int. J. Hydrogen Energy, 2017, 42: 15782
22
Zhang Q S, Zhang W, Louzguine-Luzgin D V, et al. Effect of substituting elements on glass-forming ability of the new Zr48Cu36Al8Ag8 bulk metallic glass-forming alloy[J]. J. Alloys Compd., 2010, 504: S18
23
Wu M D, Wang J C, Li P L, et al. Research progress on the anti-disproportionation of the ZrCo alloy by element substitution[J]. Materials, 2020, 13: 3977
24
Xu T, Li R, Xiao R J, et al. Tuning glass formation and brittle behaviors by similar solvent element substitution in (Mn, Fe)-based bulk metallic glasses[J]. Mater. Sci. Eng., 2015, A626: 16
25
Mitrica D, Badea I C, Serban B A, et al. Complex concentrated alloys for substitution of critical raw materials in applications for extreme conditions[J]. Materials, 2021, 14: 1197
26
Yang T, Yuan Z M, Bu W G, et al. Effect of elemental substitution on the structure and hydrogen storage properties of LaMgNi4 alloy[J]. Mater. Des., 2016, 93: 46
27
Palumbo M, Cacciamani G, Bosco E, et al. Driving forces for crystal nucleation in Fe-B liquid and amorphous alloys[J]. Intermetallics, 2003, 11: 1293
28
Okamoto H. B-Fe (Boron-Iron)[J]. J. Phase Equilib. Diffus., 2004, 25: 297
29
Massalski T B, Okamoto H, Subramanian P R, et al. Binary Alloy Phase Diagrams[M]. 2nd Ed., Materials Park: ASM International, 1990: 482
30
Raghavan V. B-Co-Fe (Boron-Cobalt-Iron)[J]. J. Phase Equilib. Diffus., 2012, 33: 392
31
Liu Y Q, Zhao X S, Yang J, et al. Thermodynamic optimization of the boron-cobalt-iron system[J]. J. Alloys Compd., 2011, 509: 4805
32
Jackson K A, Uhlmann D R, Hunt J D. On the nature of crystal growth from the melt[J]. J. Cryst. Growth, 1967, 1: 1
33
Li M J, Kuribayashi K. Nucleation-controlled microstructures and anomalous eutectic formation in undercooled Co-Sn and Ni-Si eutectic melts[J]. Metall. Mater. Trans., 2003, 34A: 2999
34
Herlach D M. Non-equilibrium solidification of undercooled metallic metals[J]. Mater. Sci. Eng., 1994, R12: 177
35
Li M J, Ozawa S, Kuribayashi K. On determining the phase-selection principle in solidification from undercooled melts-competitive nucleation or competitive growth?[J]. Philos. Mag. Lett., 2004, 84: 483
36
Turnbull D. Kinetics of solidification of supercooled liquid mercury droplets[J]. J. Chem. Phys., 1952, 20: 411
37
Turnbull D. Formation of crystal nuclei in liquid metals[J]. J. Appl. Phys., 1950, 21: 1022
38
Wei X X, Xu W, Kang J L, et al. Phase selection in solidification of undercooled Co-B alloys[J]. J. Mater. Sci. Technol., 2017, 33: 352
doi: 10.1016/j.jmst.2016.09.012
