淬火态Al-Zn-Mg-Cu合金中位错环的形成机理研究

淬火态Al-Zn-Mg-Cu合金中位错环的形成机理研究

宋  淼，齐东卿，杜  奎^*，叶恒强

（中国科学院金属研究所沈阳材料科学国家研究中心，辽宁 沈阳110016）

摘  要  采用透射电子显微镜和原位拉伸实验，研究了淬火态Al-Zn-Mg-Cu合金中三种不同组态的位错环及其形成机理。包括因Al₃Zr析出相颗粒与Al基体晶格失配及热膨胀系数差异在Al₃Zr颗粒周围形成的位错环；蜷线位错分解形成的位错环；以及因微区成分不均匀或局部缺陷导致的滑移带前端位错绕过或交滑移形成的位错环。研究表明，通过对纳米析出相在Al基体中微观组态的控制和高温淬火处理，可以调控Al合金中位错环的尺寸和三维空间分布。

关键词  铝合金；Al₃Zr；位错环；透射电子显微镜

中图分类号：TB3；TG146；TG115.21；TG111.2        

文献标识码：Adoi:10.3969/j.issn.1000-6281.2020.06.005

Formation mechanisms of dislocation loops in a quenched Al-Zn-Mg-Cu alloy

SONG Miao，QI Dong-qing，DU Kui^*，YE Heng-qiang

(Shenyang National Laboratory for Materials Science，Institute of Metal Research，Chinese Academy of Sciences，Shenyang Liaoning 110016，China)

Abstract   In this study, configurations and formation mechanisms of three types of dislocation loops in a quenched Al-Zn-Mg-Cu alloy were investigated by employing transmission electron microscopy and in situ tension experiment. The three kinds of dislocation loops are: the dislocation loops around the coherent Al₃Zr precipitates, which induced by differences of lattice mismatch and thermal expansion coefficient between Al₃Zr and Al matrix,, the dislocation loops induced by decomposition of helical dislocations, and the dislocation loops in the front of slip bands induced by bypass or cross-slip of dislocations under the effect of composition segregation or defects. The experimental results reveal the possibility of tuning the distribution and size of dislocation loops in Al alloy by controlling the coherent precipitates and quenching process, and thus improving material properties.

Keywords    Al alloy；Al₃Zr；dislocation loop；transmission electron microscopy

 “全文下载请到同方知网，万方数据库或重庆维普等数据库中下载！”

[1] LORETTO M H，CLAREBROUGH L M，HUMBLE P. The nature of dislocation loops in quenched aluminium [J]. Philosophical Magazine, 1966，13:953-961.

[2] EDINGTON J W, SMLLMAN R E. Faulted dislocation loops in quenched aluminium[J]. Philosophical Magazine, 1965，11:1109-1123.

[3] HIRSCH P B, SILCOX J, SMALLMAN R E, et al. Dislocation loops in quenched aluminium [J]. Philosophical Magazine, 1958，3:897-908.

[4] EDINGTON J W, WEST D R. Four-layer defects in quenched aluminium [J]. Philosophical Magazine, 1967，15:229-236.

[5] GAVINI V，BHATTACHARYA K，ORTIZ M. Vacancy clustering and prismatic dislocation loop formation in aluminum [J]. Physical Review B, 2007，76:180101.

[6] HALEY J C，BRIGGS S A，EDMONDSON P D，et al. Dislocation loop evolution during in-situ ion irradiation of model FeCrAl alloys [J]. Acta Materialia，2017，136:390-401.

[7] CHEN H C，LUI R D，REN C L，et al.  Evolution of dislocation loops in He ion irradiated nickel under different temperature [J]. Journal of Applied Physics，2016，120:125303.

[8] NORRIS DIR. Dislocation loop growth in an electron irradiated thin foil [J]. Philosophical Magazine，2006，22:1273-1278.

[9] FRANK F C，READ W T.  Multiplication processes for slow moving dislocations [J]. Physical Review, 1950，79:722-723.

[10] SUN F, GU Y F, YAN J B, et al. Creep deformation and rupture mechanism of an advanced wrought NiFe-based superalloy for 700℃class A-USC steam turbine rotor application [J]. Journal of Alloys and Compounds, 2016，687:389-401.

[11] SINGH C V，WARNER D H. An atomistic-based hierarchical multiscale examination of age hardening in an Al-Cu alloy [J]. Metallurgical and Materials Transactions A, 2013，44:2625-2644.

[12] REMINGTON T P，RUESTES C J，BRINGA E M，et al. Plastic deformation in nanoindentation of tantalum: a new mechanism for prismatic loop formation [J].  Acta Materialia，2014，78:378-393.

[13] EIKUM A，THOMAS G. Precipitation and dislocation nucleation in quench-aged Al-Mg alloys [J]. Acta Metallurgica, 1964，12:537-545.

[14] XIE H，GAO N，XU K，et al. A new loop-punching mechanism for helium bubble growth in tungsten [J]. Acta Materialia, 2017，141:10-17.

[15] 江彬彬，杜奎，叶恒强.  体心立方金属铌中小角晶界分解的原位电子显微学研究[J]. 电子显微学报，2019，38（2）:102-106.

[16] 翁素婷, 张庆华, 谷林.  原位电子显微学方法在材料研究中的应用[J]. 电子显微学报，2019，38（5）：556-568.

[17] TIWARI S K, CHATTOPADHYAY K, SURYANARAYANA C, et al. Decomposition studies of a liquisol quenched Al-33 at.% Mg alloy [J]. Metallography, 1979，12:73-86.

[18] DESCH P B, SCHWARZ R B, NASH P. Formation of metastable L₁₂ phases in Al₃Zr and Al-12.5%X-25%Zr (X ≡ Li, Cr, Fe, Ni, Cu) [J]. Journal of the Less Common Metals, 1991，168:69-80.

[19] ASHBY M F，BROWN L M. Diffraction contrast from spherically symmetrical coherency strains [J]. Philosophical Magazine, 1963，8:1083-1103.

[20] SONG M，DU K，HUANG Z Y, et al. Deformation-induced dissolution and growth of precipitates in an Al–Mg–Er alloy during high-cycle fatigue [J]. Acta Materialia，2014，81:409-419.

[21] MOCK M，STEIN P，HIN C，et al. Modelling the influence of strain fields around precipitates on defect equilibria and kinetics under irradiation in ODS steels: a multi scale approach [J]. Journal of Nuclear Materials, 2019，527:151807.

[22] MATSUMURA S, TOYOHARA M, TOMOKIYO Y. Strain contrast of coherent precipitates in bright-field images under zone axis incidence [J]. Philosophical Magazine A, 1990，62:653-670.

[23] LI C M，ZENG S M，CHEN Z Q，et al.  First-principles calculations of elastic and thermodynamic properties of the four main intermetallic phases in Al–Zn–Mg–Cu alloys [J]. Computational Materials Science, 2014，93:210-220.

[24] NIX F C，MACNAIR D. The thermalexpansion of pure metals: copper, gold, aluminum, nickel, and iron [J]. Physical Review, 1941，60:597-605.

[25] GUAN R，SHEN Y，ZHAO Z，et al. A high-strength, ductile Al-0.35Sc-0.2Zr alloy with good electrical conductivity strengthened by coherent nanosized-precipitates [J].  Journal of Materials Science & Technology，2017，33:215-223.

[26] VOISIN T，KRYWOPUSK N M, MOMPIOU F, et al.  Precipitation strengthening in nanostructured AZ31B magnesium thin films characterized by nano-indentation, STEM/EDS, HRTEM, and in situ TEM tensile testing [J]. Acta Materialia, 2017，138:174-184.

[27] GRIDER J T，LEIGHLY H P. Quenching defects in aluminium plus 10at.% zinc [J]. Philosophical Magazine, 1973，28:465-469.

[28] THOMAS G，WHELAN M J. Helical dislocations in quenched aluminium-4% copper alloys [J]. Philosophical Magazine, 1959，4:511-527.

[29] BURTON B，SPEIGHT M V. The coarsening and annihilation kinetics of dislocation loop [J]. Philosophical Magazine A，1986，53:385-402.

[30] ZHANG Z，MAO M M，WANG J，et al. Nanoscale origins of the damage tolerance of the high-entropy alloy CrMnFeCoNi [J]. Nature Communications，2015，6:10143.

[31] FU X，DING Q，XU Z，et al. Improving deformability of Sb₂Te₃ layered material by dislocation climb at anti-phase boundary [J]. Scripta Materialia, 2017，135:10-14.

[32] KACHER J, CUI B, ROBERTSON I M. In situ and tomographic characterization of damage and dislocation processes in irradiated metallic alloys by transmission electron microscopy [J]. Journal of Materials Research, 2015，30:1202-1213.