Liquid lithium first wall is an advanced concept in the field of magnetic confinement fusion. Compared with the traditional solid wall materials, more and more experiments have shown that liquid lithium wall has unique advantages, which can not only effectively solve a series of problems faced by solid wall materials such as sputtering and tritium retention, but also significantly improve the constraint performance of core plasma. However, liquid lithium has brought severe corrosion problems to most metal materials, and the microstructure changes caused by corrosion will inevitably lead to the degradation of the macroscopic mechanical properties of materials. For structural materials, the degradation of mechanical properties will bring safety risks to the entire device. Based on this, the uniaxial tensile simulations of single crystal alpha-iron were carried out by using molecular dynamics, and the effects of lithium atoms on the plastic deformation behavior and yield stress were analyzed in this paper. The results show that lithium atoms can significantly suppress the phase transition, change the plastic deformation mode of alpha-iron, and affect the yield stress and its relationship with temperature.
[1] Federici G, Skinner C H, Brooks J N, et al. Plasma-material interactions in current tokamaks and their implications for next step fusion reactors[J]. Nucl Fusion, 2001, 41(12):1967-2137.
[2] Küppers J. The hydrogen surface chemistry of carbon as a plasma facing material[J]. Surface Science Reports, 1995, 22(7/8):249-321.
[3] Roth J, Tsitrone E, Loarer T, et al. Tritium inventory in ITER plasma-facing materials and tritium removal procedures[J]. Plasma Physics and Controlled Fusion, 2008, 50(10):103001.
[4] Scotti F, Soukhanovskii V A, Bell R E, et al. Core transport of lithium and carbon in ELM-free discharges with lithium wall conditioning in NSTX[J]. Nucl Fusion, 2013, 53(8):083001.
[5] Abdou M A, Team T A, Ying A, et al. On the exploration of innovative concepts for fusion chamber technology[J]. Fusion Eng Des, 2001, 54(2):181-247.
[6] Chopra O K, Tortorelli P F. Compatibility of materials for use in liquid-metal blankets of fusion reactors[J]. J Nucl Mater, 1984, 123(1-3):1201-1212.
[7] Chopra O K, Smith D L. Influence of temperature and lithium purity on corrosion of ferrous alloys in a flowing lithium environment[J]. J Nucl Mater, 1986, 141-143(Part 2):584-591.
[8] Flament T, Tortorelli P, Coen V, et al. Compatibility of materials in fusion first wall and blanket structures cooled by liquid metals[J]. J Nucl Mater, 1992, 191-194(Part A):132-138.
[9] Popovich V V, Shtykalo I G, Chaevskii M I. Effect of lithium on the mechanical properties of armco iron[J]. Soviet Materials Science:a Transl of Fiziko-Khimicheskaya Mekhanika Materialov/Academy of Sciences of the Ukrainian SSR, 1967, 3(2):88-93.
[10] Chopra O, Smith D. Low-cycle fatigue behavior of HT9 alloy in a flowing-lithium environment[C]//Davis J W, Michel D J. Proceedings of the topical conference on ferritic alloys for use in nuclear energy technologies. State of Utah:Snowbird Press, 1984:8.
[11] Mustari A P A, Takahashi M. Metallurgical analysis of corroded bellows of bellow-sealed valve in lithium flow system[J]. Fusion Eng Des, 2013, 88(4):202-208.
[12] Webb E B, Grest G S, Heine D R. Precursor film controlled wetting of Pb on Cu[J]. Phys Rev Lett, 2003, 91(23):236102.
[13] Palafox-Hernandez J P, Laird B B, Asta M. Atomistic characterization of the Cu-Pb solid-liquid interface[J]. Acta Mater, 2011, 59(8):3137-3144.
[14] Gan X L, Xiao S F, Deng H Q, et al. Atomistic simulations of the Fe(001)-Li solid-liquid interface[J]. Fusion Eng Des, 2014, 89(12):2894-2901.
[15] Mendelev M I, Han S, Srolovitz D J, et al. Development of new interatomic potentials appropriate for crystalline and liquid iron[J]. Philos Mag, 2003, 83(35):3977-3994.
[16] Tsai D H. The virial theorem and stress calculation in molecular dynamics[J]. J Chem Phys, 1979, 70(3):1375-1382.
[17] Nichol A, Ackland G J. Property trends in simple metals:an empirical potential approach[J]. Phy Rev B, 2016, 93(18):184101.
[18] Plimpton S. Fast Parallel Algorithms for short-range molecular dynamics[J]. J Comput Phys, 1995, 117(1):1-19.
[19] Stukowski A. Visualization and analysis of atomistic simulation data with OVITO-the open visualization tool[J]. Model Simul Mater Sci Eng, 2010, 18(1):015012.
[20] Honeycutt J D, Andersen H C. Molecular dynamics study of melting and freezing of small Lennard-Jones clusters[J]. J Phys Chem, 1987, 91(19):4950-4963.
[21] Stukowski A, Bulatov V V, Arsenlis A. Automated identification and indexing of dislocations in crystal interfaces[J]. Model Simul Mater Sci Eng, 2012, 20(8):085007.
[22] Hagen A B, Snartland B D, Thaulow C. Temperature and orientation effects on the deformation mechanisms of α-Fe micropillars[J]. Acta Mater, 2017, 129:398-407.
[23] Feng Y X, Shang J X, Qin S J, et al. Twin and dislocation mechanisms in tensile W single crystal with temperature change:a molecular dynamics study[J]. Phys Chem Chem Phys, 2018, 20(26):17727-17738.
[24] Molnar D, Binkele P, Hocker S, et al. Atomistic multiscale simulations on the anisotropic tensile behaviour of copper-alloyed alpha-iron at different states of thermal ageing[J]. Philos Mag, 2012, 92(5):586-607.
[25] Friák M, Šob M. Ab initio study of the bcc-hcp transformation in iron[J]. Phys Rev B, 2008, 77(17):174117.
[26] Zhu T, Li J, Samanta A, et al. Temperature and strain-rate dependence of surface dislocation nucleation[J]. Phys Rev Lett, 2008, 100(2):025502.
[27] Zuo L, Ngan A H W. Molecular dynamics study on compressive yield strength in Ni3Al micro-pillars[J]. Phil Mag Lett, 2006, 86(6):355-365.
[28] Hepburn D J, MacLeod E, Ackland G J. Transition metal solute interactions with point defects in fcc iron from first principles[J]. Phys Rev B, 2015, 92(1):014110.
[29] Devi E A, Chinnappan R, Sundar C S. First-principles study of interaction energies of atomic defects in bcc ferromagnetic iron[J]. Phys Rev B, 2018, 98(14):144104.
[30] Weinberger C R, Cai W. Plasticity of metal nanowires[J]. Journal of Materials Chemistry, 2012, 22(8):3277-3292.
[31] Rabkin E, Nam H S, Srolovitz D J. Atomistic simulation of the deformation of gold nanopillars[J]. Acta Mater, 2007, 55(6):2085-2099.
[32] Adams J J, Agosta D S, Leisure R G, et al. Elastic constants of monocrystal iron from 3 to 500 K[J]. J Appl Phys, 2006, 100(11):113530.
[33] Černý M, Šesták P, Pokluda J. Strength of bcc crystals under combined shear and axial loading from first principles[J]. Comp Mater Sci, 2012, 55:337-343.
[34] Kotrechko S, Ovsjannikov A. Temperature dependence of the yield stress of metallic nano-sized crystals[J]. Philos Mag, 2009, 89(33):3049-3058.
