Precipitation-assisted heterostructure in a FeMnCoCrCuC high entropy alloy enables superior mechanical property

Abstract

High-entropy alloys in which the face-centered cubic structure is dominant cannot meet practical engineering application requirements due to their insufficient strength. Traditional strengthening methods can improve strength of materials, but they inevitably lead to decreased ductility. In this work, mechanical properties of a face-centered cubic-structured FeMnCoCrCu high-entropy alloy were improved by doping a substantial amount of carbon and employing a processing route that combines cold rolling and annealing. A dual-heterostructure characterized by both bimodal grain-size distribution and non-uniform distribution of nanoscale precipitates was constructed. The average grain sizes were 21.6 and 5.9 μm for the coarse and fine grains, accounting for 56.6% and 43.4% of the material, respectively. On the other hand, the finer M₂₃C₆ precipitates in the grain interior had an average size of 73.1 nm, constituting 3.4% of the coarse-grained region and 10.7% of the fine-grained region. The larger M₂₃C₆ precipitates at grain boundaries had an average size of 182.4 nm, with an overall volume fraction of 1.5%. This heterogeneous microstructure endowed the alloy with superior strength and work-hardening capacity compared to the carbon-free alloy. The yield and tensile strengths reached 500 MPa and 979 MPa, respectively, while maintaining a uniform elongation of 42%. This study not only identifies the origin of strengthening and micromechanism of plastic deformation in the carbon-alloyed dual-heterostructured alloy but also elucidates the formation of the specified microstructure. The findings provide theoretical guidance for developing advanced alloys with both high strength and good ductility.

Keywords

High-entropy alloy / carbon doping / heterostructure / precipitate / mechanical property

References

[1] Yeh J,Lin S.Nanostructured high-entropy alloys with multiple principal elements: novel alloy design concepts and outcomes.Adv Eng Mater2004;6:299-303

[2] Cantor B,Knight P.Microstructural development in equiatomic multicomponent alloys.Mater Sci Eng A2004;375-377:213-8

[3] He Z,Yan H.Multi-heterostructure and mechanical properties of N-doped FeMnCoCr high entropy alloy.Int J Plast2021;139:102965

[4] He Z,Sun L.Interstitial-driven local chemical order enables ultrastrong face-centered cubic multicomponent alloys.Acta Mater2023;243:118495

[5] Li Z,Deng Y,Tasan CC.Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off.Nature2016;534:227-30

[6] Marques F,Winkelmann F,Felderhoff M.Review and outlook on high-entropy alloys for hydrogen storage.Energy Environ Sci2021;14:5191-227

[7] Liu Y,Zhang X,Gao M.Superior catalytic activity derived from a two-dimensional Ti₃C₂ precursor towards the hydrogen storage reaction of magnesium hydride.Chem Commun2016;52:705-8

[8] Pang Y,Gao M.A mechanical-force-driven physical vapour deposition approach to fabricating complex hydride nanostructures.Nat Commun2014;5:3519

[9] Zhang X,Ren Z.Realizing 6.7 wt% reversible storage of hydrogen at ambient temperature with non-confined ultrafine magnesium hydrides.Energy Environ Sci2021;14:2302-13

[10] Min J,He Z,Chen W.Superior mechanical properties and multiple strengthening mechanisms of a V-alloyed FeMnCoCr high-entropy alloy.Mater Sci Eng A2024;902:146614

[11] Li Z.Strong and ductile non-equiatomic high-entropy alloys: design, processing, microstructure, and mechanical properties.JOM2017;69:2099-106 PMCID:PMC6954013

[12] Li Z,Springer H,Raabe D.Interstitial atoms enable joint twinning and transformation induced plasticity in strong and ductile high-entropy alloys.Sci Rep2017;7:40704 PMCID:PMC5227964

[13] Zhang H,Zhang J,Fang F.Ultrahigh strength induced by multiple heterostructures in a FeMnCoCrN high-entropy alloy fabricated by powder metallurgy technique.Mater Sci Eng A2022;846:143304

[14] Su J,Li Z.Hierarchical microstructure design to tune the mechanical behavior of an interstitial TRIP-TWIP high-entropy alloy.Acta Mater2019;163:40-54

[15] Yuan Y,Wei J,Yan H.Cu alloying enables superior strength-ductility combination and high corrosion resistance of FeMnCoCr high entropy alloy.J Alloy Compd2024;970:172543

[16] Li Z,Pradeep KG.A TRIP-assisted dual-phase high-entropy alloy: grain size and phase fraction effects on deformation behavior.Acta Mater2017;131:323-35

[17] Zhu Y.Heterostructured materials.Prog Mater Sci2023;131:101019

[18] Zhu Y T. Introduction to heterostructured materials. Oxford: Elsevier; 2023. pp. 9-10. Available from: https://doi.org/10.1016/C2021-0-00963-9. [Last accessed on 17 Mar 2025]

[19] Li A,Gao Y,Li G.Ultra-high strength and excellent ductility high entropy alloy induced by nano-lamellar precipitates and ultrafine grain structure.Mater Sci Eng A2023;862:144286

[20] Yang Y,Jiang S.Achieving exceptional strength and ductility combination in a heterostructured Mg-Y alloy with densely refined twins.J Mater Scie Technol2024;189:132-45

[21] Wu X,Yuan F.Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility.Proc Natl Acad Sci U S A2015;112:14501-5 PMCID:PMC4664339

[22] Li J,Gao B,Zhu Y.Superior strength and ductility of 316L stainless steel with heterogeneous lamella structure.J Mater Sci2018;53:10442-56

[23] Zhang Z,Vajpai SK,Ameyama K.Importance of bimodal structure topology in the control of mechanical properties of a stainless steel.Adv Eng Mater2015;17:791-5

[24] Zhang Z,Orlov D.Improvement of mechanical properties in SUS304L steel through the control of bimodal microstructure characteristics.Mater Sci Eng A2014;598:106-13

[25] Yang Y,Yan S.On the micromechanism of superior strength and ductility synergy in a heterostructured Mg-2.77Y alloy.J Magnes Alloys2024;12:2793-811

[26] Pu Z,Dai L.Effective strengthening and toughening in high entropy-alloy by combining extrusion machining and heat treatment.Scr Mater2022;213:114630

[27] Sun W,Chan YY,Yang X.An extraordinary-performance gradient nanostructured Hadfield manganese steel containing multi-phase nanocrystalline-amorphous core-shell surface layer by laser surface processing.J Mater Sci Technol2023;134:209-22

[28] Sun Y,Wang Z.Superior mechanical properties and deformation mechanisms of a 304 stainless steel plate with gradient nanostructure.Int J Plast2022;155:103336

[29] Wang Z,Zhao H.Ultrastrong lightweight compositionally complex steels via dual-nanoprecipitation.Sci Adv2020;6 PMCID:PMC7673736

[30] Li G,Lyu S.Simultaneously enhanced strength and strain hardening capacity in FeMnCoCr high-entropy alloy via harmonic structure design.Scr Mater2021;191:196-201

[31] Jiang S,Hegedűs Z.Micromechanical behavior of multilayered Ti/Nb composites processed by accumulative roll bonding: an in-situ synchrotron X-ray diffraction investigation.Acta Mater2021;205:116546

[32] Li A,Li R.Double heterogeneous structures induced excellent strength-ductility synergy in Ni₄₀Co₃₀Cr₂₀A_l5Ti₅ medium-entropy alloy.J Mater Scie Technol2024;181:176-88

[33] Guo S,Xia G.Pursuing ultrastrong and ductile medium entropy alloys via architecting nanoprecipitates-enhanced hierarchical heterostructure.Acta Mater2024;263:119492

[34] Zhao G,Li J,Liu H.Effect of copper on edge cracking behavior and microstructure of rolled austenitic stainless steel plate.J Iron Steel Res Int2022;29:281-94

[35] Gao J,Zhang H.Facile route to bulk ultrafine-grain steels for high strength and ductility.Nature2021;590:262-7 PMCID:PMC7888382

[36] Wang X,Jiao L.Inhibition of the intergranular brittleness of HR3C heat-resistant steel by strain-aging induced nano-M₂₃C₆ dispersion precipitation.J Mater Scie Technol2025;213:288-99

[37] Weygand D,Lépinoux J.Zener pinning and grain growth: a two-dimensional vertex computer simulation.Acta Mater1999;47:961-70

[38] Humphreys F.Grain boundary migration and zener pinning in particle-containing copper crystals.Acta Mater1996;44:2717-27

[39] Moon J,Kim HS.Twinning Engineering of a CoCrFeMnNi high-entropy alloy.Scr Mater2021;197:113808

[40] He Z,Wang H,Shen Y.Synergy effect of multi-strengthening mechanisms in FeMnCoCrN HEA at cryogenic temperature.J Mater Sci Technol2021;86:158-70

[41] Zhang Z.Consideration of Orowan strengthening effect in particulate-reinforced metal matrix nanocomposites: a model for predicting their yield strength.Scr Mater2006;54:1321-6

[42] Wu Y,Chen Q.Strengthening and fracture mechanisms of a precipitation hardening high-entropy alloy fabricated by selective laser melting.Virtual Phys Prototyp2022;17:451-67

[43] Zhang Q.A model for predicting the particle size dependence of the low cycle fatigue life in discontinuously reinforced MMCs.Scr Mater2004;51:863-7

[44] Mecking H.Kinetics of flow and strain-hardening.Acta Metall1981;29:1865-75

[45] Dini G,Najafizadeh A.Flow stress analysis of TWIP steel via the XRD measurement of dislocation density.Mater Sci Eng A2010;527:2759-63

[46] Liu S,Guo H,Misra R.The significance of multi-step partitioning: Processing-structure-property relationship in governing high strength-high ductility combination in medium-manganese steels.Acta Mater2017;124:159-72

[47] Sun LF,Jia N.Local chemical order enables an ultrastrong and ductile high-entropy alloy in a cryogenic environment.Sci Adv2024;10:eadq6398 PMCID:PMC11606435

[48] Basu I.Strengthening mechanisms in high entropy alloys: Fundamental issues.Scr Mater2020;187:148-56

[49] Biswas K,Bhattacharjee PP.High entropy alloys: key issues under passionate debate.Scr Mater2020;188:54-8

[50] Zhu Y.Perspective on hetero-deformation induced (HDI) hardening and back stress.Mater Res Lett2019;7:393-8

[51] Yang M,Yuan F,Wu X.Back stress strengthening and strain hardening in gradient structure.Mater Res Lett2016;4:145-51

[52] Picak S,Hayrettin C.Anomalous work hardening behavior of Fe₄₀Mn₄₀Cr₁₀Co₁₀ high entropy alloy single crystals deformed by twinning and slip.Acta Mater2019;181:555-69

[53] Ming K,Wang J.Strength and ductility of CrFeCoNiMo alloy with hierarchical microstructures.Int J Plast2019;113:255-68

[54] Laplanche G,Horst O,George E.Microstructure evolution and critical stress for twinning in the CrMnFeCoNi high-entropy alloy.Acta Mater2016;118:152-63

[55] Wang J,Yang H.Ultrastrong and ductile (CoCrNi)₉₄Ti₃Al₃ medium-entropy alloys via introducing multi-scale heterogeneous structures.J Mater Sci Technol2023;135:241-9

[56] Liu X,Fan X.Excellent strength-ductility combination in Co₃₆Cr₁₅Fe₁₈Ni₁₈Al₈Ti₄Mo₁ multi-principal element alloys by dual-morphology B2 precipitates strengthening.J Mater Sci Technol2023;134:60-6