A novel immiscible high entropy alloy strengthened via L1₂-nanoprecipitate

Abstract

The low-cost Fe-Cu, Fe-Ni, and Cu-based high-entropy alloys exhibit a widespread utilization prospect. However, these potential applications have been limited by their low strength. In this study, a novel Fe₃₁Cu₃₁Ni₂₈Al₄Ti₃Co₃ immiscible high-entropy alloy (HEA) was developed. After vacuum arc melting and copper mold suction casting, this HEA exhibits a unique phase separation microstructure, which consists of striped Cu-rich regions and Fe-rich region. Further magnification of the striped Cu-rich region reveals that it is composed of a Cu-rich dot-like phase and a Fe-rich region. The aging alloy is further strengthened by a L1₂-Ni₃(AlTi) nanoprecipitates, achieving excellent yield strength (1185 MPa) and uniform ductility (∼8.8%). The differential distribution of the L1₂ nanoprecipitate in the striped Cu-rich region and the external Fe-rich region increased the strength difference between these two regions, which increased the strain gradient and thus improved hetero-deformation induced (HDI) hardening. This work provides a new route to improve the HDI hardening of Fe-Cu alloys.

Keywords

heterogeneous microstructure / precipitation strengthening / high-entropy alloy / phase separation / mechanical property

References

[1] Cantor B, Chang I T H, Knight P, et al.. Microstructural development in equiatomic multicomponent alloys [J]. Materials Science and Engineering A, 2004, 375–377: 213-218,

[2] Yeh J W, Chen S K, Lin S J, et al.. Nanostructured high-entropy alloys with multiple principal elements: Novel alloy design concepts and outcomes [J]. Advanced Engineering Materials, 2004, 6(5): 299-303,

[3] Zhang Yong. . High-entropy materials: A brief introduction [M], 2019 Singapore Springer Singapore,

[4] Li Z-z, Zhao S-t, Ritchie R O, et al.. Mechanical properties of high-entropy alloys with emphasis on face-centered cubic alloys [J]. Progress in Materials Science, 2019, 102: 296-345,

[5] Li S-c, Wang Q-l, Yao Y, et al.. Application of high-pressure technology in exploring mechanical properties of high-entropy alloys [J]. Tungsten, 2023, 5(1): 50-66,

[6] Liu L-y, Zhang Y, Han J-h, et al.. Nanoprecipitate-strengthened high-entropy alloys [J]. Advanced Science, 2021, 8(23): e2100870,

[7] Khallaf A H, Bhlol M, Dawood O M, et al.. Wear resistance, hardness, and microstructure of carbide dispersion strengthened high-entropy alloys [J]. Journal of Central South University, 2022, 29(11): 3529-3543,

[8] Yang B-z, Xiong X, Liu R-t, et al.. Effect of carbon on microstructure, mechanical properties and wear resistance of non-equiatomic Fe₇₀Co_7.5Cr_7.5Ni_7.5V_7.5 medium-entropy alloys fabricated by powder metallurgy [J]. Journal of Central South University, 2022, 29(6): 1799-1810,

[9] Chen X-f, Wang Q, Cheng Z-y, et al.. Direct observation of chemical short-range order in a medium-entropy alloy [J]. Nature, 2021, 592(7856): 712-716,

[10] Yuan L-j, Tao R, Wen P-c, et al.. Molecular dynamics simulation of chemical short-range order strengthening in FCC FeNiCrCoAl alloys [J]. Physica B: Condensed Matter, 2023, 649: 414447,

[11] Moon J, Park J M, Bae J W, et al.. A new strategy for designing immiscible medium-entropy alloys with excellent tensile properties [J]. Acta Materialia, 2020, 193: 71-82,

[12] Sathiyamoorthi P, Kim H S. High-entropy alloys with heterogeneous microstructure: Processing and mechanical properties [J]. Progress in Materials Science, 2022, 123: 100709,

[13] Wu X-l, Zhu Y-tian. Heterogeneous materials: A new class of materials with unprecedented mechanical properties [J]. Materials Research Letters, 2017, 5(8): 527-532,

[14] Andreoli A F, Orava J, Liaw P K, et al.. The elastic-strain energy criterion of phase formation for complex concentrated alloys [J]. Materialia, 2019, 5: 100222,

[15] Verma A, Tarate P, Abhyankar A C, et al.. High temperature wear in CoCrFeNiCu_x high entropy alloys: The role of Cu [J]. Scripta Materialia, 2019, 161: 28-31,

[16] He M Y, Shen Y F, Jia N, et al.. Achieving sustainable strain hardening in a carbon-doped CuFeMnNi high-entropy alloy via dual-level heterogeneous microstructures [J]. Journal of Alloys and Compounds, 2023, 939: 168831,

[17] Shim S H, Pouraliakbar H, Minouei H, et al.. Characterization of the microscale/nanoscale hierarchical microstructure of an as-cast CrMnFeNiCu high-entropy alloy with promising mechanical properties [J]. Journal of Alloys and Compounds, 2023, 954: 170091,

[18] Liu L-y, Zhang Y, Li J-p, et al.. Enhanced strength-ductility synergy via novel bifunctional nanoprecipitates in a high-entropy alloy [J]. International Journal of Plasticity, 2022, 153: 103235,

[19] Yang T, Zhao Y L, Tong Y, et al.. Multicomponent intermetallic nanoparticles and superb mechanical behaviors of complex alloys [J]. Science, 2018, 362(6417): 933-937,

[20] Fan L, Yang T, Zhao Y-l, et al.. Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures [J]. Nature Communications, 2020, 11(1): 6240,

[21] Du X H, Li W P, Chang H T, et al.. Dual heterogeneous structures lead to ultrahigh strength and uniform ductility in a Co-Cr-Ni medium-entropy alloy [J]. Nature Communications, 2020, 11(1): 2390,

[22] Antonov S, Detrois M, Tin S. Design of novel precipitate-strengthened Al-Co-Cr-Fe-Nb-Ni high-entropy superalloys [J]. Metallurgical and Materials Transactions A, 2018, 49(1): 305-320,

[23] Zhang Y-t, Liu M-w, Sun J-y, et al.. Excellent thermal stability and mechanical properties of bulk nanostructured FeCoNiCu high entropy alloy [J]. Materials Science and Engineering A, 2022, 835: 142670,

[24] Shim S H, Pouraliakbar H, Hong S I. Hierarchical structured as-cast CrFeNiMn_0.5Cu_0.5 high entropy alloy with excellent tensile strength/ductility properties [J]. Scripta Materialia, 2022, 210: 114473,

[25] Sun X-d, Zhu H-g, Li J-l, et al.. High entropy alloy FeCoNiCu matrix composites reinforced with in situ TiC particles and graphite whiskers [J]. Materials Chemistry and Physics, 2018, 220: 449-459,

[26] Song S C, Moon J, Kim H S. Hetero-deformation-induced strengthening of multi-phase Cu-Fe-Mn medium entropy alloys by dynamic heterostructuring [J]. Materials Science and Engineering A, 2021, 799: 6,

[27] Qiu H, Zhu H-g, Zhang J-f, et al.. Effect of Fe content upon the microstructures and mechanical properties of Fe_xCoNiCu high entropy alloys [J]. Materials Science and Engineering A, 2020, 769: 138514,

[28] Qin G, Chen R-r, Mao H-h, et al.. Experimental and theoretical investigations on the phase stability and mechanical properties of Cr₇Mn₂₅Co₉Ni₂₃Cu₃₆ high-entropy alloy [J]. Acta Materialia, 2021, 208: 116763,

[29] Qin G, Chen R-r, Liaw P K, et al.. A novel face-centered-cubic high-entropy alloy strengthened by nanoscale precipitates [J]. Scripta Materialia, 2019, 172: 51-55,

[30] Sarkar S, Srivastava C, Chattopadhyay K. Development of a new class of high strength copper alloy using immiscibility route in Cu-Fe-Si system: Evolution of hierarchical multi-scale microstructure [J]. Materials Science and Engineering A, 2018, 723: 38-47,

[31] Shen Q, Xiong X-y, Li T, et al.. Effects of Co-addition of Ni and Al on precipitation evolution and mechanical properties of Fe-Cu alloy [J]. Materials Science and Engineering A, 2018, 723: 279-286,

[32] Kakisawa H, Minagawa K, Halada K. Tensile behavior change depending on the microstructure of a Fe-Cu alloy produced from rapidly solidified powder [J]. Materials Science and Engineering A, 2003, 340(1–2): 175-180,

[33] Ahles A A, Emery J D, Dunand D C. Mechanical properties of meteoritic Fe - Ni alloys for in situ extraterrestrial structures [J]. Acta Astronautica, 2021, 189: 465-475,

[34] Huang K-l, Zhang Y, Zhang Z-w, et al.. Coupling precipitation strengthening and transformation induced plasticity to produce a superior combination of strength and ductility in a high entropy alloy [J]. Journal of Alloys and Compounds, 2022, 929: 167356,

[35] Ma Y-x, Zhang Y, Zhang Z-w, et al.. Two novel Zr-rich refractory high-entropy alloys with excellent tensile mechanical properties [J]. Intermetallics, 2023, 157: 107872,

[36] Zheng D, Li R-d, Yuan T-c, et al.. Microstructure and mechanical property of additively manufactured NiTi alloys: A comparison between selective laser melting and directed energy deposition [J]. Journal of Central South University, 2021, 28(4): 1028-1042,

[37] He J Y, Wang H, Huang H L, et al.. A precipitation-hardened high-entropy alloy with outstanding tensile properties [J]. Acta Materialia, 2016, 102: 187-196,

[38] Gao N, Hu Q, Wang Y S, et al.. Controlled precipitation and strengthening in a CuFeNiMn medium-entropy alloy [J]. Materials Science and Engineering A, 2022, 852: 143694,

[39] Dasari S, Jagetia A, Sharma A, et al.. Tuning the degree of chemical ordering in the solid solution of a complex concentrated alloy and its impact on mechanical properties [J]. Acta Materialia, 2021, 212: 116938,

[40] Cheng Z, Wan T, Bu L-f, et al.. Effect of volume fractions of gradient transition layer on mechanical behaviors of nanotwinned Cu [J]. Acta Materialia, 2023, 242: 118456,

[41] Wu X-l, Zhu Y-t, Lu Ke. Ductility and strain hardening in gradient and lamellar structured materials [J]. Scripta Materialia, 2020, 186: 321-325,