超低温环境下亚稳态CoCrFeNi高熵合金的优异塑性和锯齿流变行为（英文）
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摘要
低温环境下,位错的运动受到限制而导致极少数的金属和合金能保持优异的力学性能,尤其是塑性.本文研究了具有面心立方结构的CoCrFeNi高熵合金的超低温服役,发现其在低温环境下具有优异的综合性能. 4.2 K时的拉伸强度达到1260 MPa,同时延伸率达到62%,展现出极强的低温应用潜力;超低温环境下,高熵合金极低的层错促进了变形孪晶的产生,使其表现出高强高韧的优异力学性能.此外,在液氦环境下,该合金中FCC-HCP的相转变和锯齿流变行为使得合金在77 K以下温度的塑性降低;同时,关于锯齿特征的动态模型分析证实由于相变行为的出现导致该合金中锯齿行为的不稳定特点.液氦环境下,大量的变形孪晶和相变行为的共同作用导致了较高的应变硬化率,从而使高熵合金的塑性变形维持在较高的应力水平,并且形成了锯齿特征.
Seldom could metals and alloys maintain excellent properties in cryogenic condition, such as the ductility, owing to the restrained dislocation motion.However, a face-centered-cubic(FCC) CoCrFeNi highentropy alloy(HEA) with great ductility is investigated under the cryogenic environment. The tensile strength of this alloy can reach a maximum at 1,251±10 MPa, and the strain to failure can stay at as large as 62% at the liquid helium temperature. We ascribe the high strength and ductility to the low stacking fault energy at extremely low temperatures,which facilitates the activation of deformation twinning.Moreover, the FCC→HCP(hexagonal close-packed) transition and serration lead to the sudden decline of ductility below 77 K. The dynamical modeling and analysis of serrations at 4.2 and 20 K verify the unstable state due to the FCC→HCP transition. The deformation twinning together with phase transformation at liquid helium temperature produces an adequate strain-hardening rate that sustains the stable plastic flow at high stresses, resulting in the serration feature.
Seldom could metals and alloys maintain excellent properties in cryogenic condition, such as the ductility, owing to the restrained dislocation motion.However, a face-centered-cubic(FCC) CoCrFeNi highentropy alloy(HEA) with great ductility is investigated under the cryogenic environment. The tensile strength of this alloy can reach a maximum at 1,251±10 MPa, and the strain to failure can stay at as large as 62% at the liquid helium temperature. We ascribe the high strength and ductility to the low stacking fault energy at extremely low temperatures,which facilitates the activation of deformation twinning.Moreover, the FCC→HCP(hexagonal close-packed) transition and serration lead to the sudden decline of ductility below 77 K. The dynamical modeling and analysis of serrations at 4.2 and 20 K verify the unstable state due to the FCC→HCP transition. The deformation twinning together with phase transformation at liquid helium temperature produces an adequate strain-hardening rate that sustains the stable plastic flow at high stresses, resulting in the serration feature.
引文
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28 Ren JL,Chen C,Liu ZY,et al.Plastic dynamics transition between chaotic and self-organized critical states in a glassy metal via a multifractal intermediate.Phys Rev B,2012,86:134303
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31 Packard NH,Crutchfield JP,Farmer JD,et al.Geometry from a time series.Phys Rev Lett,1980,45:712-716
32 Fraser AM,Swinney HL.Independent coordinates for strange attractors from mutual information.Phys Rev A,1986,33:1134-1140
33 Cao L.Practical method for determining the minimum embedding dimension of a scalar time series.Physica D-Nonlinear Phenomena,1997,110:43-50
34 Wolf A,Swift JB,Swinney HL,et al.Determining Lyapunov exponents from a time series.Physica D-Nonlinear Phenomena,1985,16:285-317
35 http://www.copper.org/resources/properties/144_8/
36 Estrin Y,Isaev NV,Lubenets SV,et al.Effect of microstructure on plastic deformation of Cu at low homologous temperatures.Acta Mater,2006,54:5581-5590
37 Tobler RL,Berger JR,Bussiba A.Long-crack fatigue thresholds and short crack simulation at liquid helium temperature.In:Fickett FR,Reed RP(eds.).Advances in Cryogenic Engineering:Materials.Boston:Springer,1992,159-166
38 Das A,Tarafder S.Geometry of dimples and its correlation with mechanical properties in austenitic stainless steel.Scripta Mater,2008,59:1014-1017
39 Otto F,DlouhyA,Somsen C,et al.The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy.Acta Mater,2013,61:5743-5755
40 Huang S,Li W,Lu S,et al.Temperature dependent stacking fault energy of FeCrCoNiMn high entropy alloy.Scripta Mater,2015,108:44-47
41 Zhang F,Wu Y,Lou H,et al.Polymorphism in a high-entropy alloy.Nat Commun,2017,8:15687
42 Pustovalov VV.Serrated deformation of metals and alloys at low temperatures.Low Temperature Phys,2008,34:683-723
43 Zhang Y,Liu JP,Chen SY,et al.Serration and noise behaviors in materials.Prog Mater Sci,2017,90:358-460
44 Antonaglia J,Xie X,Tang Z,et al.Temperature effects on deformation and serration behavior of high-entropy alloys(HEAs).JOM,2014,66:2002-2008
45 Tirunilai AS,Sas J,Weiss KP,et al.Peculiarities of deformation of CoCrFeMnNi at cryogenic temperatures.J Mater Res,2018,33:3287-3300
46 Gr?ssel O,Krüger L,Frommeyer G,et al.High strength Fe-Mn-(Al,Si)TRIP/TWIP steels development-properties-application.Int J Plast,2000,16:1391-1409
47 Li Z,Pradeep KG,Deng Y,et al.Metastable high-entropy dualphase alloys overcome the strength-ductility trade-off.Nature,2016,534:227-230
48 Lin Q,Liu J,An X,et al.Cryogenic-deformation-induced phase transformation in an FeCoCrNi high-entropy alloy.Mater Res Lett,2018,6:236-243
49 Miao J,Slone CE,Smith TM,et al.The evolution of the deformation substructure in a Ni-Co-Cr equiatomic solid solution alloy.Acta Mater,2018,132:35-48
2 Yang H,Huang C,Wu Z,et al.Analysis on the structural transformation of ITER TF conductor jacket tube.Adv Eng Mater,2015,17:305-310
3 Ogata T,Nagai K,Ishikawa K.Vamas tests of structural materials at liquid helium temperature.In:Reed RP,Fickett FR,Summers LT,Stieg M(eds.).Advances in Cryogenic Engineering Materials.Boston:Springer,1994,1191-1198
4 Wang Y,Ma E,Valiev R,et al.Tough nanostructured metals at cryogenic temperatures.Adv Mater,2004,16:328-331
5 Gludovatz B,Hohenwarter A,Catoor D,et al.A fracture-resistant high-entropy alloy for cryogenic applications.Science,2014,345:1153-1158
6 Gludovatz B,Hohenwarter A,Thurston KVS,et al.Exceptional damage-tolerance of a medium-entropy alloy CrCoNi at cryogenic temperatures.Nat Commun,2016,7:10602
7 Jo YH,Jung S,Choi WM,et al.Cryogenic strength improvement by utilizing room-temperature deformation twinning in a partially recrystallized VCrMnFeCoNi high-entropy alloy.Nat Commun,2017,8:15719
8 Deng Y,Tasan CC,Pradeep KG,et al.Design of a twinninginduced plasticity high entropy alloy.Acta Mater,2015,94:124-133
9 Laplanche G,Kostka A,Horst OM,et al.Microstructure evolution and critical stress for twinning in the CrMnFeCoNi high-entropy alloy.Acta Mater,2016,118:152-163
10 Zhu YT,Liao XZ,Srinivasan SG,et al.Nucleation and growth of deformation twins in nanocrystalline aluminum.Appl Phys Lett,2014,85:5049-5051
11 Blewitt TH,Coltman RR,Redman JK.Low-temperature deformation of copper single crystals.J Appl Phys,1957,28:651-660
12 Zhu YT,Liao XZ,Wu XL.Deformation twinning in nanocrystalline materials.Prog Mater Sci,2012,57:1-62
13 Wu Z,Bei H,Pharr GM,et al.Temperature dependence of the mechanical properties of equiatomic solid solution alloys with face-centered cubic crystal structures.Acta Mater,2014,81:428-441
14 Liu B,Wang J,Liu Y,et al.Microstructure and mechanical properties of equimolar FeCoCrNi high entropy alloy prepared via powder extrusion.Intermetallics,2016,75:25-30
15 Huo W,Zhou H,Fang F,et al.Strain-rate effect upon the tensile behavior of CoCrFeNi high-entropy alloys.Mater Sci Eng-A,2017,689:366-369
16 Huo W,Fang F,Zhou H,et al.Remarkable strength of CoCrFeNi high-entropy alloy wires at cryogenic and elevated temperatures.Scripta Mater,2017,141:125-128
17 Zhang Y,Zuo TT,Tang Z,et al.Microstructures and properties of high-entropy alloys.Prog Mater Sci,2014,61:1-93
18 Miracle DB,Senkov ON.A critical review of high entropy alloys and related concepts.Acta Mater,2017,122:448-511
19 Lyu Z,Fan X,Lee C,et al.Fundamental understanding of mechanical behavior of high-entropy alloys at low temperatures:Areview.J Mater Res,2018,33:2998-3010
20 Laktionova MA,Tabchnikova ED,Tang Z,et al.Mechanical properties of the high-entropy alloy Ag0.5CoCrCuFeNi at temperatures of 4.2-300 K.Low Temperature Phys,2013,39:630-632
21 Qiao JW,Ma SG,Huang EW,et al.Microstructural characteristics and mechanical behaviors of AlCoCrFeNi high-entropy alloys at ambient and cryogenic temperatures.MSF,2011,688:419-425
22 Zhang W,Liaw PK,Zhang Y.Science and technology in highentropy alloys.Sci China Mater,2018,61:2-22
23 Li DY,Zhang Y.The ultrahigh charpy impact toughness of forged AlxCoCrFeNi high entropy alloys at room and cryogenic temperatures.Intermetallics,2016,70:24-28
24 Vicsek T.Fractal growth phenomena.Singapore:World Scientific,1992
25 Chen C,Ren J,Wang G,et al.Scaling behavior and complexity of plastic deformation for a bulk metallic glass at cryogenic temperatures.Phys Rev E,2015,92:012113
26 Chen S,Yu L,Ren J,et al.Self-similar random process and chaotic behavior in serrated flow of high entropy alloys.Sci Rep,2016,6:29798
27 Ren JL,Chen C,Wang G,et al.Dynamics of serrated flow in a bulk metallic glass.AIP Adv,2011,1:032158
28 Ren JL,Chen C,Liu ZY,et al.Plastic dynamics transition between chaotic and self-organized critical states in a glassy metal via a multifractal intermediate.Phys Rev B,2012,86:134303
29 Guo X,Xie X,Ren J,et al.Plastic dynamics of the Al0.5CoCrCuFeNi high entropy alloy at cryogenic temperatures:Jerky flow,stair-like fluctuation,scaling behavior,and non-chaotic state.Appl Phys Lett,2017,111:251905
30 Takens F.Detecting strange attractors in turbulence.In:Rand D,Young LS(eds).Dynamical Systems and Turbulence,Warwick1980.Lecture Notes in Mathematics,vol 898.Heidelberg:Springer,1981,366-381
31 Packard NH,Crutchfield JP,Farmer JD,et al.Geometry from a time series.Phys Rev Lett,1980,45:712-716
32 Fraser AM,Swinney HL.Independent coordinates for strange attractors from mutual information.Phys Rev A,1986,33:1134-1140
33 Cao L.Practical method for determining the minimum embedding dimension of a scalar time series.Physica D-Nonlinear Phenomena,1997,110:43-50
34 Wolf A,Swift JB,Swinney HL,et al.Determining Lyapunov exponents from a time series.Physica D-Nonlinear Phenomena,1985,16:285-317
35 http://www.copper.org/resources/properties/144_8/
36 Estrin Y,Isaev NV,Lubenets SV,et al.Effect of microstructure on plastic deformation of Cu at low homologous temperatures.Acta Mater,2006,54:5581-5590
37 Tobler RL,Berger JR,Bussiba A.Long-crack fatigue thresholds and short crack simulation at liquid helium temperature.In:Fickett FR,Reed RP(eds.).Advances in Cryogenic Engineering:Materials.Boston:Springer,1992,159-166
38 Das A,Tarafder S.Geometry of dimples and its correlation with mechanical properties in austenitic stainless steel.Scripta Mater,2008,59:1014-1017
39 Otto F,DlouhyA,Somsen C,et al.The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy.Acta Mater,2013,61:5743-5755
40 Huang S,Li W,Lu S,et al.Temperature dependent stacking fault energy of FeCrCoNiMn high entropy alloy.Scripta Mater,2015,108:44-47
41 Zhang F,Wu Y,Lou H,et al.Polymorphism in a high-entropy alloy.Nat Commun,2017,8:15687
42 Pustovalov VV.Serrated deformation of metals and alloys at low temperatures.Low Temperature Phys,2008,34:683-723
43 Zhang Y,Liu JP,Chen SY,et al.Serration and noise behaviors in materials.Prog Mater Sci,2017,90:358-460
44 Antonaglia J,Xie X,Tang Z,et al.Temperature effects on deformation and serration behavior of high-entropy alloys(HEAs).JOM,2014,66:2002-2008
45 Tirunilai AS,Sas J,Weiss KP,et al.Peculiarities of deformation of CoCrFeMnNi at cryogenic temperatures.J Mater Res,2018,33:3287-3300
46 Gr?ssel O,Krüger L,Frommeyer G,et al.High strength Fe-Mn-(Al,Si)TRIP/TWIP steels development-properties-application.Int J Plast,2000,16:1391-1409
47 Li Z,Pradeep KG,Deng Y,et al.Metastable high-entropy dualphase alloys overcome the strength-ductility trade-off.Nature,2016,534:227-230
48 Lin Q,Liu J,An X,et al.Cryogenic-deformation-induced phase transformation in an FeCoCrNi high-entropy alloy.Mater Res Lett,2018,6:236-243
49 Miao J,Slone CE,Smith TM,et al.The evolution of the deformation substructure in a Ni-Co-Cr equiatomic solid solution alloy.Acta Mater,2018,132:35-48