基于分子动力学模拟的纳米铝板力学性能与缺陷演化过程的尺寸效应研究
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摘要
采用分子动力学方法模拟了不同分子动力学模型尺寸对含初始裂纹缺陷纳米单晶铝板在拉伸载荷作用下的裂纹缺陷演化过程的影响。结果表明:随着模型尺寸增大,材料的屈服应力减小,屈服点提前,断裂韧性提高。在弹性阶段,材料变形与体系内部原子的点缺陷和面缺陷相关;在塑性变形阶段,材料变形与位错增殖和滑移相关。裂纹尖端处应力集中是裂尖附近晶体结构发生相变的原因,能量在相变后释放导致应力松弛所致。
The size effects on the mechanical properties and defect evolution process of single crystal aluminum with a center crack under tensile loading have been simulated through molecular dynamic method. With the increase of model size, the yield stress and yield point decreased, while the fracture toughness increased. In the elastic stage, the deformation relies heavily on the point defects and surface defects in materials, while in plastic stage it depends strongly on the dislocation multiplication and its slip. The stress concentration at the crack tip is mainly associated with the phase transformation of the crystal structure near the crack tip due to the stress relaxation after phase transformation.
The size effects on the mechanical properties and defect evolution process of single crystal aluminum with a center crack under tensile loading have been simulated through molecular dynamic method. With the increase of model size, the yield stress and yield point decreased, while the fracture toughness increased. In the elastic stage, the deformation relies heavily on the point defects and surface defects in materials, while in plastic stage it depends strongly on the dislocation multiplication and its slip. The stress concentration at the crack tip is mainly associated with the phase transformation of the crystal structure near the crack tip due to the stress relaxation after phase transformation.
引文
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[13] MISHIN Y, FARCKAS D, MEHL M J, et al. Interatomic potentials for monoatomic metals from experimental data and ab-initio calculations [J]. Physics Review Series B, 1999, 59(5): 3393-3407.
[14] LIAO Yi, XIANG Meizeng, ZENG xiangguo. Molecular dynamics studies of the roles of microstructure and thermal effects in spallation of aluminum[J]. Mechanics of Materials, 2015(84): 12-27.
[15] 赵亚溥. 纳米与介观力学 [M]. 北京: 科学出版社, 2014:4.ZHAO YaPu. Nano and MESOSCOPIC Mechanics [M]. Beijing: Science Press, 2014:4 (In Chinese).
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[17] NOSE S. A unified formulation of the constant temperature molecular dynamics methods[J]. The Journal of Chemical Physics, 1984, 81(1):511.
[18] KELCHNER C L, PLIMPTON S J, HAMITON J C. Dislocation nucleation and defect structure during surface indentation[J]. Physics Review Series B, 1998, 58 (17):11085-11088.
[19] Li Duo, Wang Fengchao, Yang Zhenyu, et al. How to identify dislocations in molecular dynamics simulations?[J]. Science China Physics, Mechanics & Astronomy, 2014, 57(12): 2177-2187.
[20] DANIEL F, HANNES J. Systematic analysis of local atomic structure combined with 3D computer graphics[J]. Computational Materials Science. 1994, 2(2):279-286.
[21] TSUZUKI H, BRANICIO P S, RINO J P. Structural characterization of deformed crystals by analysis of common atomic neighborhood[J]. Computer Physics Communications, 2007, 177(6): 518-523.
[22] YANG W D, YANG F P, WANG X. Dynamic instability and bifurcation of electrically actuated circular nanoplate considering surface behavior and small scale effect [J]. International Journal of Mechanical Sciences, 2017(126):12-23.
[23] 郭宇,庄茁,李晓雁. FCC金属塑性屈服的尺寸效应和应变率响应[J]. 力学学报,2006, 38(3):398-406.GUO Yu, ZHUANG Zhuo, LI XiaoYan, Effects of specimen size and applied strain rate on the plastic flow of FCC metals[J]. Chinese Journal of Theoretical and Applied Mechanics, 2006, 38(3):398-406 (In Chinese).
[24] 解德,钱勤,李长安. 断裂力学中的数值计算方法与应用[M]. 北京:科学出版社,2009:5.XIE De, QIAN Qin, LI ChanGan, Numerical simulation and application in fracture mechanics [M]. Beijing: Science Press,2009:5 (In Chinese).
[25] MITTENMEIJER E J. Fundamentals of Materials Science [M]. Berlin: Springer, 2010:201.
[26] 李萍,赵宾,薛克敏. 铜合金微塑性成形力学性能及其本构关系[J]. 固体力学学报, 2015, 36(5):401-409.LI Ping, ZHAO Bin, XUE KeMin. Mechanical properties of copper alloy during micro-plastic and its constitutive model[J]. Chinese Journal of Solid Mechanics, 2015, 36(5):401-409 (In Chinese).
[27] HELMUT S, MICHAEL F L, CARSTEN D, et al. Cyclopentadienylderivate von Aluminium(I)[J]. Journal of Organometallic Chemistry, 1998, 561(1-2):203-208.
[28] NISHIMURA K, MIYAZAKI N. Molecular dynamics simulation of crack propagation in polycrystalline material [J]. Computer Modeling in Engineering & Sciences, 2001, 2(2):143-153.
[29] NISHIMURA K, MIYAZAKI N. Molecular dynamics simulation of crack growth under cyclic loading [J]. Computational Materials Science, 2004, 31(3-4):269-278.
[30] TSCHOPP M A, SPEAROT D E, MCDOWELL D L. Atomistic simulations of homogeneous dislocation nucleation in single crystal copper [J]. Modeling and Simulation in Materials Science and Engineering, 2007(15):693-709.
[31] KOLLURI K, GUNGOR M R, MAROUDAS D. Molecular dynamics simulation of martensitic fcc-to-hcp phase transformations in strained ultrathin metallic films [J]. Physics Review series B, 2008(78):195408.
[32] 王哲,张钧,李述军,等. 模型尺寸对电子束逐层熔化成形Ti-6Al-4V合金组织和力学性能的影响[J]. 稀有金属材料与工程, 2014, 43(1):161-164.WANG Zhe, ZHANG Jun, LI ShuJun, et al. Effects of part size on microstructure and mechanical properties of ti-6al-4v alloy fabricated by electron beam melting [J]. Rare Metal Materials And Engineering, 2014, 43(1):161-164 (In Chinese).
[33] GEERS M G D, BREKELMANS W A M, JANSSEN P J M. Size effects in miniaturized polycrystalline FCC samples: strengthening versus weakening [J]. International Journal of Solids and Structures, 2006 (43): 7304-7321.
[2] 王鹏,徐建刚,张云光,等. 晶粒尺寸对纳米多晶铁变形机制影响的模拟研究[J]. 物理学报, 2016, 65(23):1-6.WANG Peng, XU JianGang, ZHANG YunGuang, et al. Molecular dynamics simulation of effect of grain on mechanical properties of nano-polycrystal α-Fe[J]. Acta Physics Sinnica, 2016, 65(23):1-6 (In Chinese).
[3] SAMANTHA K L, YURIY Y, HANNU H, et al. Effects of grain size and deformation temperature on hydrogen-enhanced vacancy formation in Ni alloys[J]. Acta Materialia, 2017(128):218-226.
[4] MOHAMMADZADEH M, MOHAMMADZADEH R. Effect of grain size on apparent diffusivity in nanocrystal a-iron by atomistic simulation[J]. Computational Materials Science, 2017(129): 239-246.
[5] 余隽,唐祯安,魏广芬. 微电子机械系统中微尺度热物性研究进展[J]. 机械强度, 2001, 23(4):465-470.YU Jun,TANG ZhenAn, WEI GuangFen. Progress of study on microscale thermal properties of micro-electro-mechanical systems[J]. Journal of Mechanical Strength, 2001, 23(4):465-470 (In Chinese).
[6] 文玉华,朱如曾,周富信,等.分子动力学模拟的主要技术[J].力学进展, 2003, 23(1):65-73.WENYuHua, ZHU RuZeng, ZHOU FuXin, et al. Main technology of molecular dynamics simulation[J]. Advances in Mechanics, 2003, (23)1:65-73 (In Chinese).
[7] MAHATO J K, De P S, SARKAR A, et al. Effect of deformation mode and grain size on Bauschinger behavior of annealed copper[J]. International Journal of Fatigue, 2016, 83: 42-52.
[8] REN Junqiang, SUN Qiaoyan, XIAO Lin, et al. Size-dependent of compression yield strength and deformation mechanism in titanium single-crystal nanopillars orientated [0001] and [112ˉ0] [J]. Materials Science & Engineering A, 2014, 615: 22-28.
[9] DUNSTAN D J, BUSHBY A J. The scaling exponent in the size effect of small scale plastic deformation [J]. International Journal of Plasticity, 2013, 40:152-162.
[10] MOHAMMADREZA Y, VOYIADJIS G Z. Size effects in fcc crystals during the high rate compression test [J]. Acta Materialia, 2016, 121:190-201.
[11] HORSTEMEYER M F, BASKES M L, PLIMOTON S J. Computational nanoscale plasticity simulations using embedded atom potentials. Theoretical and Applied Fracture Mechanics, 2001, 37(1): 37-49.
[12] 刘光勇. 有孔纳米单晶铜薄膜拉伸断裂特性的分子动力学模拟[J]. 机械强度, 2004, 26(S):084-086.LIU GuangYong. Molecular dynamics simulation of fracture behavior of the single-crystalline nano-copper film with a hole[J]. Journal of Mechanical Strength, 2004, 26(S):084-086 (In Chinese).
[13] MISHIN Y, FARCKAS D, MEHL M J, et al. Interatomic potentials for monoatomic metals from experimental data and ab-initio calculations [J]. Physics Review Series B, 1999, 59(5): 3393-3407.
[14] LIAO Yi, XIANG Meizeng, ZENG xiangguo. Molecular dynamics studies of the roles of microstructure and thermal effects in spallation of aluminum[J]. Mechanics of Materials, 2015(84): 12-27.
[15] 赵亚溥. 纳米与介观力学 [M]. 北京: 科学出版社, 2014:4.ZHAO YaPu. Nano and MESOSCOPIC Mechanics [M]. Beijing: Science Press, 2014:4 (In Chinese).
[16] SWOPE W C, ANDERSEN H C, BERENS P H, et al. A computer simulation method for the calculation of equilibrium constants for the formation of physical clusters of molecules: application to small water clusters[J]. The Journal of Chemical Physics, 1982, 76(1): 637-649.
[17] NOSE S. A unified formulation of the constant temperature molecular dynamics methods[J]. The Journal of Chemical Physics, 1984, 81(1):511.
[18] KELCHNER C L, PLIMPTON S J, HAMITON J C. Dislocation nucleation and defect structure during surface indentation[J]. Physics Review Series B, 1998, 58 (17):11085-11088.
[19] Li Duo, Wang Fengchao, Yang Zhenyu, et al. How to identify dislocations in molecular dynamics simulations?[J]. Science China Physics, Mechanics & Astronomy, 2014, 57(12): 2177-2187.
[20] DANIEL F, HANNES J. Systematic analysis of local atomic structure combined with 3D computer graphics[J]. Computational Materials Science. 1994, 2(2):279-286.
[21] TSUZUKI H, BRANICIO P S, RINO J P. Structural characterization of deformed crystals by analysis of common atomic neighborhood[J]. Computer Physics Communications, 2007, 177(6): 518-523.
[22] YANG W D, YANG F P, WANG X. Dynamic instability and bifurcation of electrically actuated circular nanoplate considering surface behavior and small scale effect [J]. International Journal of Mechanical Sciences, 2017(126):12-23.
[23] 郭宇,庄茁,李晓雁. FCC金属塑性屈服的尺寸效应和应变率响应[J]. 力学学报,2006, 38(3):398-406.GUO Yu, ZHUANG Zhuo, LI XiaoYan, Effects of specimen size and applied strain rate on the plastic flow of FCC metals[J]. Chinese Journal of Theoretical and Applied Mechanics, 2006, 38(3):398-406 (In Chinese).
[24] 解德,钱勤,李长安. 断裂力学中的数值计算方法与应用[M]. 北京:科学出版社,2009:5.XIE De, QIAN Qin, LI ChanGan, Numerical simulation and application in fracture mechanics [M]. Beijing: Science Press,2009:5 (In Chinese).
[25] MITTENMEIJER E J. Fundamentals of Materials Science [M]. Berlin: Springer, 2010:201.
[26] 李萍,赵宾,薛克敏. 铜合金微塑性成形力学性能及其本构关系[J]. 固体力学学报, 2015, 36(5):401-409.LI Ping, ZHAO Bin, XUE KeMin. Mechanical properties of copper alloy during micro-plastic and its constitutive model[J]. Chinese Journal of Solid Mechanics, 2015, 36(5):401-409 (In Chinese).
[27] HELMUT S, MICHAEL F L, CARSTEN D, et al. Cyclopentadienylderivate von Aluminium(I)[J]. Journal of Organometallic Chemistry, 1998, 561(1-2):203-208.
[28] NISHIMURA K, MIYAZAKI N. Molecular dynamics simulation of crack propagation in polycrystalline material [J]. Computer Modeling in Engineering & Sciences, 2001, 2(2):143-153.
[29] NISHIMURA K, MIYAZAKI N. Molecular dynamics simulation of crack growth under cyclic loading [J]. Computational Materials Science, 2004, 31(3-4):269-278.
[30] TSCHOPP M A, SPEAROT D E, MCDOWELL D L. Atomistic simulations of homogeneous dislocation nucleation in single crystal copper [J]. Modeling and Simulation in Materials Science and Engineering, 2007(15):693-709.
[31] KOLLURI K, GUNGOR M R, MAROUDAS D. Molecular dynamics simulation of martensitic fcc-to-hcp phase transformations in strained ultrathin metallic films [J]. Physics Review series B, 2008(78):195408.
[32] 王哲,张钧,李述军,等. 模型尺寸对电子束逐层熔化成形Ti-6Al-4V合金组织和力学性能的影响[J]. 稀有金属材料与工程, 2014, 43(1):161-164.WANG Zhe, ZHANG Jun, LI ShuJun, et al. Effects of part size on microstructure and mechanical properties of ti-6al-4v alloy fabricated by electron beam melting [J]. Rare Metal Materials And Engineering, 2014, 43(1):161-164 (In Chinese).
[33] GEERS M G D, BREKELMANS W A M, JANSSEN P J M. Size effects in miniaturized polycrystalline FCC samples: strengthening versus weakening [J]. International Journal of Solids and Structures, 2006 (43): 7304-7321.