界面结构对Cu/Ni多层膜纳米压痕特性影响的分子动力学模拟
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摘要
金属多层膜调制周期下降到纳米级时,其力学性质会发生显著改变. Cu-Ni晶格失配度约为2.7%,可以形成共格界面和半共格界面,实验中实现沿[111]方向生长的调制周期为几纳米且具有异孪晶界面结构的Cu/Ni多层膜,其力学性质发生显著改变.本文采用分子动力学方法对共格界面、共格孪晶界面、半共格界面、半共格孪晶界面等四种不同界面结构的Cu/Ni多层膜进行纳米压痕模拟,研究压痕过程中不同界面结构类型的形变演化规律以及位错与界面的相互作用,获取Cu/Ni多层膜不同界面结构对其力学性能的影响特征.计算结果表明,不同界面结构的样品在不同压痕深度时表现出的强化或软化作用机理不同,软化机制主要是由于形成了平行于界面的分位错以及孪晶界面的迁移,强化机制主要是由于界面对位错的限定作用以及失配位错网状结构与孪晶界面迁移时所形成的弓形位错之间的相互作用.
The mechanical properties of metal multilayers change significantly when the modulation period decreases to a nanoscale. As is well known, the lattice misfit between Ni and Cu is ～2.7%, it means that the coherent and semicoherent interfaces can form between the Ni and Cu atomic layer. Hetero-twin interface Cu/Ni multilayer film with a modulation period of several nanometers and grown along the [111] direction is realized experimentally, and the mechanical properties change significantly due to the effect of interfaces. In this study, molecular dynamics simulations on Cu/Ni multilayers with coherent, coherent twin, semi-coherent, and semi-coherent twin interfaces under nanoindentation are carried out to study the deformation evolutions of different interfaces and the interactions between dislocation and interfaces. Furthermore, the influence of Cu/Ni interface on the mechanical property is investigated. The simulation results show that the different interface structures exhibit different strengthening and/or softening mechanisms at different indentation depths. The hardness values of the Cu/Ni multilayer films with four different interface structures are different,and the hardness of the coherent interface is larger than the semi-coherent interface's. The hardness values of the four interface structures reside between the pure Cu and pure Ni. For the coherent twin interface, with the increase of the modulation ratio, the strengthening effect of the twin interface is enhanced. The softening effect for the coherent interface is mainly attributed to the generation of parallel dislocations and their proliferation. While for the semi-coherent interface, the mismatched networks are formed at the Cu/Ni interfaces, the softening effect on the movable dislocation is mainly the repulsion of the mismatched network, while the strengthening effect on the movable dislocation is the hindrance of the mismatched dislocation network. The strengthening of the coherent twin interface is attributed to the limited effect of twin interface on the movable dislocation within the monolayer. Unlike the coherent twin interface,the strengthening effect of the semi-coherent twin interface is mainly due to the mutual repulsion between the arched dislocation, which is generated within the twin interface, and the mismatched network. Furthermore, the pinning effect of misfit dislocation network will impede the migration of twin interfaces and will also enhance the mechanical property of Cu/Ni multilayer film.
The mechanical properties of metal multilayers change significantly when the modulation period decreases to a nanoscale. As is well known, the lattice misfit between Ni and Cu is ～2.7%, it means that the coherent and semicoherent interfaces can form between the Ni and Cu atomic layer. Hetero-twin interface Cu/Ni multilayer film with a modulation period of several nanometers and grown along the [111] direction is realized experimentally, and the mechanical properties change significantly due to the effect of interfaces. In this study, molecular dynamics simulations on Cu/Ni multilayers with coherent, coherent twin, semi-coherent, and semi-coherent twin interfaces under nanoindentation are carried out to study the deformation evolutions of different interfaces and the interactions between dislocation and interfaces. Furthermore, the influence of Cu/Ni interface on the mechanical property is investigated. The simulation results show that the different interface structures exhibit different strengthening and/or softening mechanisms at different indentation depths. The hardness values of the Cu/Ni multilayer films with four different interface structures are different,and the hardness of the coherent interface is larger than the semi-coherent interface's. The hardness values of the four interface structures reside between the pure Cu and pure Ni. For the coherent twin interface, with the increase of the modulation ratio, the strengthening effect of the twin interface is enhanced. The softening effect for the coherent interface is mainly attributed to the generation of parallel dislocations and their proliferation. While for the semi-coherent interface, the mismatched networks are formed at the Cu/Ni interfaces, the softening effect on the movable dislocation is mainly the repulsion of the mismatched network, while the strengthening effect on the movable dislocation is the hindrance of the mismatched dislocation network. The strengthening of the coherent twin interface is attributed to the limited effect of twin interface on the movable dislocation within the monolayer. Unlike the coherent twin interface,the strengthening effect of the semi-coherent twin interface is mainly due to the mutual repulsion between the arched dislocation, which is generated within the twin interface, and the mismatched network. Furthermore, the pinning effect of misfit dislocation network will impede the migration of twin interfaces and will also enhance the mechanical property of Cu/Ni multilayer film.
引文
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[19]Plimpton S 1995 J.Comput.Phys.117 1
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[21]Johnson R A 1989 Phys.Rev.B:Condens.Matter 3912554
[22]Zhou X W,Wadley H N G 1998 J.Appl.Phys.84 2301
[23]Chang W Y,Fang T H,Lin S J,Huang J J 2010 Mol.Simul.36 815
[24]Imran M,Hussain F,Rashid M,Ahmad S A 2012 Chin.Phys.B 21 126802
[25]Hepburn D J,Ackland G J 2008 Phys.Rev.B:Condens.Matter 78
[26]Fu T,Peng X,Weng S,Zhao Y,Gao F,Deng L 2016Mater.Sci.Eng.A 658 1
[27]Stukowski A 2012 Modell.Simul.Mater.Sci.Eng.20045021
[28]Zhu Y X,Li Z H,Huang M S,Liu Y 2015 Int.J.Plast.72 168
[29]Cheng D,Yan Z J,Yan L 2007 Thin Solid Films 5153698
[30]Huang C,Peng X H,Fu T,Chen X,Xiang H,Li Q 2017Mater.Sci.Eng.A 700 609
[2]Li X,Bhushan B,Takashima K,Baek C W,Kim Y K2003 Ultramicroscopy 97 481
[3]Huang G S,Mei Y F 2016 Sci.China:Technol.46 142(in Chinese)[黄高山,梅永丰2016中国科学:技术科学46142]
[4]Huang G,Mei Y 2012 Adv.Mater.24 2517
[5]Clemens B M,Kung H,Barnett S A 1999 MRS Bull.2420
[6]Misra A,Verdier M,Lu Y C,Kung H,Mitchell T E,Nastasi M 1998 Scripta Mater.39 555
[7]Koehler J S 1970 Phys.Rev.B 2 547
[8]Embury J D,Hirth J P 1994 Acta Metall.Mater.422051
[9]Mckeown J,Misra A,Kung H,Hoagland R G,Nastasi M 2002 Scripta Mater.46 593
[10]Zhao Y,Peng X,Fu T,Sun R,Feng C,Wang Z 2015Physica E 74 481
[11]Yan X L,Coetsee E,Wang J Y,Swart H C,Terblans JJ 2017 Appl.Surf.Sci.411 73
[12]Ren F,Zhao S,Li W,Tian B,Yin L,Volinsky A A 2011Mater.Lett.65 119
[13]Zhu X Y,Liu X J,Zong R L,Zeng F,Pan F 2010 Mater.Sci.Eng.A 527 1243
[14]Weng S,Ning H,Hu N,Yan C,Fu T,Peng X 2016Mater.Des.111 1
[15]Fu T,Peng X,Xiang C,Weng S,Ning H,Li Q 2016 Sci.Reports 6 35665
[16]Cheng D,Yan Z J,Yan L 2008 Acta Metall.Sin.44 12(in Chinese)[程东,严志军,严立2008金属学报44 12]
[17]Liu Y,Bufford D,Rios S,et al.2012 J.Appl.Phys.111118
[18]Yuan L,Jing P,Liu Y H,Xu Z H,Shan D B,Guo B2014 Acta Phys.Sin.63 016201(in Chinese)[袁林,敬鹏,刘艳华,徐振海,单德彬,郭斌2014物理学报63 016201]
[19]Plimpton S 1995 J.Comput.Phys.117 1
[20]Foiles S M,Baskes M I,Daw M S 1986 Phys.Rev.B 337983
[21]Johnson R A 1989 Phys.Rev.B:Condens.Matter 3912554
[22]Zhou X W,Wadley H N G 1998 J.Appl.Phys.84 2301
[23]Chang W Y,Fang T H,Lin S J,Huang J J 2010 Mol.Simul.36 815
[24]Imran M,Hussain F,Rashid M,Ahmad S A 2012 Chin.Phys.B 21 126802
[25]Hepburn D J,Ackland G J 2008 Phys.Rev.B:Condens.Matter 78
[26]Fu T,Peng X,Weng S,Zhao Y,Gao F,Deng L 2016Mater.Sci.Eng.A 658 1
[27]Stukowski A 2012 Modell.Simul.Mater.Sci.Eng.20045021
[28]Zhu Y X,Li Z H,Huang M S,Liu Y 2015 Int.J.Plast.72 168
[29]Cheng D,Yan Z J,Yan L 2007 Thin Solid Films 5153698
[30]Huang C,Peng X H,Fu T,Chen X,Xiang H,Li Q 2017Mater.Sci.Eng.A 700 609