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【综述】纳米材料中的形变孪晶

jiejie54lsj 举报此信息
纳米材料中的形变孪生机制很有意思,我最近找了一篇综述来看,分享给大家。
另外推荐Koch的《Structural Nanocrystalline Materials》,论坛里就有,,大家可以去下来看,这里就不贴出来了。
Y.T. Zhu , X.Z. Liao , X.L. Wu
Y.T.Zhu Department of Materials Science & Engineering, North Carolina State University, Raleigh, NC 27695, USA
X.Z. Liao School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
X.L. Wu State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China
Abstract
Nanocrystalline (nc) materials can be defined as solids with grain sizes in the range of 1–100 nm. Contrary to coarse-grained metals, which become more difficult to twin with decreasing grain size, nanocrystalline face-centered-cubic (fcc) metals become easier to twin with decreasing grain size, reaching a maximum twinning probability, and then become more difficult to twin when the grain size decreases further, i.e. exhibiting an inverse grain-size effect on twinning. Molecular dynamics simulations and experimental observations have revealed that the mechanisms of deformation twinning in nanocrystalline metals are different from those in their coarse-grained counterparts. Consequently, there are several types of deformation twins that are observed in nanocrystalline materials, but not in coarse-grained metals. It has also been reported that deformation twinning can be utilized to enhance the strength and ductility of nanocrystalline materials. This paper reviews all aspects of deformation twinning in nanocrystalline metals, including deformation twins observed by molecular dynamics simulations and experiments, twinning mechanisms, factors affecting the twinning, analytical models on the nucleation and growth of deformation twins, interactions between twins and dislocations, and the effects of twins on mechanical and other properties. It is the authors’ intention for this review paper to serve not only as a valuable reference for researchers in the field of nanocrystalline metals and alloys, but also as a textbook for the education of graduate students.
Content
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Basics of deformation twinning in fcc metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Deformation twinning in coarse-grained fcc metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Twinning mechanisms in coarse-grained fcc metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Grain size effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3. Temperature and strain rate effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Deformation mechanisms in nanocrystalline materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1. Grain boundary sliding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. Grain rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.3. Dislocation emission from grain boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.4. Stacking fault and deformation twinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Deformation twinning in nanocrystalline fcc materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. Molecular dynamics simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2. Experimental observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3. Twinning mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3.1. Overlapping of stacking fault ribbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.3.2. Partial emission from grain boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3.3. Twinning with low macroscopic strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.3.4. Grain boundary splitting and migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3.5. Sequential twinning mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3.6. Partial multiplication at twin boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.3.7. Dislocation rebound mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.4. Grain size effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.5. General planar fault energy effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
5.6. Non-equilibrium grain boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5.7. Strain rate and temperature effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5.8. Twin nucleation and growth models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.8.1. Conventional dislocation model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.8.2. Partial emission from grain boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.8.3. Twinning partial from grain boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.8.4. General-planar-fault-energy (GPFE) based models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.8.5. Future issues on modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6. Deformation twinning in non-fcc metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6.1. Deformation twinning in nanocrystalline bcc metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
6.2. Deformation twinning in nanocrystalline hcp metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
7. Interaction between dislocations and twin boundaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.1. Cross slip of a 30 partial  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
7.2. Transmission of a 30 partial across twin boundary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.3. Reaction of a 90 partial at twin boundary  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
7.4. Reaction of a perfect screw dislocation at twin boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.5. Reaction of a perfect 60 dislocation at twin boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.5.1. Partials first constrict to form a perfect 60 dislocation . . . . . . . . . . . . . . . . . . . . . . . . . 46
7.5.2. 30 leading partial reacts first at twin boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
7.5.3. 90 leading partial reacts first at twin boundary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
8. Effect of twinning on properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.1. Strain rate sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
8.2. Strain hardening rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.3. Strength and ductility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8.4. Fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
8.5. Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9. Outstanding issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
10. Implications of deformation twinning within materials science. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
11. Summary and concluding remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . 57
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