He注入对W在瞬态热负荷条件下熔化行为的影响
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摘要
通过多峰He离子注入的方式在W表面获得了约450 nm深的均匀损伤平台,并且通过改变离子注量控制损伤程度为0.2～1.0 dPa。利用瞬态热反射法测量了表层亚微米级别损伤层的热导率,并进一步依托电子束实验平台EMS-60研究了损伤材料在瞬态热负荷下的熔化行为。结果表明, He离子注入在W表层形成了高密度的He团簇,损伤层热导相比于块体材料下降了1个数量级,并且随着损伤程度的升高而下降。损伤W在瞬态热负荷条件下的熔化阈值由1.9 GW·m~(-2)下降至1.5 GW·m~(-2)以下,熔化阈值同样随着损伤程度的增加而降低,并且在熔池外部出现裂纹。研究表明表面亚微米的损伤结构会强烈损伤W在瞬态热负荷下的熔化行为;损伤层的热导率很好地反映了损伤程度,并与热负荷行为相吻合,将微观损伤与宏观性能建立了联系。
A multi-peak He ion implantation method was used to obtain a uniform damage surface about 450 nm deep on W surface. The damage degree was controlled to 0.2～1.0 dPa by changing the ion fluence. The thermal conductivity of the sub-micron damage layer in the surface layer was measured by the transient heat reflection method. The melting behavior of the damaged W under transient heat load was further studied utilizing the electron beam experimental platform EMS-60. The results showed that He ion implantation formed a high-density He cluster on the W surface, and the thermal conductivity of the damaged layer decreased by one order of magnitude compared to the bulk material and decreased with the increase of the damage degree. The melting threshold of the damaged W under transient thermal loading decreased from 1.9 GW·m~(-2) to less than 1.5 GW·m~(-2). The melting threshold also decreased with increasing damage, and cracks appeared outside the weld pool. It was shown that the surface sub-micrometer damage structure would strongly damage the melting behavior of W under transient thermal loading. The thermal conductivity of the damaged layer well reflected the degree of damage, and was consistent with the thermal load behavior. The micro-damage and the melting behavior were connected by the thermal conductivity.
A multi-peak He ion implantation method was used to obtain a uniform damage surface about 450 nm deep on W surface. The damage degree was controlled to 0.2～1.0 dPa by changing the ion fluence. The thermal conductivity of the sub-micron damage layer in the surface layer was measured by the transient heat reflection method. The melting behavior of the damaged W under transient heat load was further studied utilizing the electron beam experimental platform EMS-60. The results showed that He ion implantation formed a high-density He cluster on the W surface, and the thermal conductivity of the damaged layer decreased by one order of magnitude compared to the bulk material and decreased with the increase of the damage degree. The melting threshold of the damaged W under transient thermal loading decreased from 1.9 GW·m~(-2) to less than 1.5 GW·m~(-2). The melting threshold also decreased with increasing damage, and cracks appeared outside the weld pool. It was shown that the surface sub-micrometer damage structure would strongly damage the melting behavior of W under transient thermal loading. The thermal conductivity of the damaged layer well reflected the degree of damage, and was consistent with the thermal load behavior. The micro-damage and the melting behavior were connected by the thermal conductivity.
引文
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[18] Dechaumphai E,Barton J L,Tesmer J R,Moon J,Wang Y.Near-surface thermal characterization of plasma facing components using the 3-omega method [J].Journal of Nuclear Materials,2014,455:56.
[19] Armstrong D E J,Edmondson P D,Roberts S G.Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten [J].Applied Physics Letter,2013,102(25):251901.
[2] Chen L,Xu G S,Nielsen A H,Gao W,Duan Y M.Study on the L-H transition power threshold with RF heating and lithium-wall coating on EAST [J].Nuclear Fusion,2016,56:056013.
[3] Hammond K D.Helium,hydrogen,and fuzz in plasma-facing materials [J].Materials Research Express,2017,4:104002.
[4] Philipps V,Roth J,Loarte A.Key issues in plasma-wall interactions for ITER:a european approach [J].Plasma Physics and Controlled Fusion,2003,45 (12A):A17.
[5] Malykhin S V,Surovitskiy S V,Makhlaj V A,Aksenov N N,Byrka O V,Borisova S S,Herashchenko S S,Reshetnyak V V.Structure evolution of tungsten coatings exposed to plasma flows under ITER ELM relevant conditions [J].Problems of Atomic Science and Technology,2017,107(1):123.
[6] Garkusha I E,Bandura A N,Byrka O V,Chebotarev V V,Landman I S,Makhlaj V A,Marchenko A K,Solyakov D G,Tereshin V I,Trubchaninov S A,Tsarenko A V.Tungsten erosion under plasma heat loads typical for ITER type I ELMs and disruptions [J].Journal of Nuclear Materials,2005,337:707.
[7] Nishijima D,Doerner R P,Iwamoto D,Kikuchi Y,Miyamoto M,Nagata M,Sakuma I,Shoda K,Ueda Y.Response of fuzzy tungsten surfaces to pulsed plasma bombardment [J].Journal of Nuclear Materials,2014,434:230.
[8] Tian X G,Zhang Y L,Li S Y,Huang Z P,Wang R.Temperature distribution with different solid shapes in heat transfer process [J].Chinese Journal of Rare Metals,2017,41(4):377.(田晓根,张亚莉,李少英,黄志鹏,王茹.传热过程中固体形状对温度分布的影响分析 [J].稀有金属,2017,41(4):377.)
[9] Yuan Y,Greuner H,Boeswirth B,Luo G N,Fu B Q,Xu H Y,Liu W.Melt layer erosion of pure and lanthanum doped tungsten under VDE-like high heat flux loads [J].Journal of Nuclear Materials,2013,438S:S229.
[10] Qu S L,Li Y F,Wang Z G,Jia Y Z,Li C,Xu Ben,Chen W Q,Bai S Y,Huang Z X,Tang Z A,Liu W.Thermal conductivity measurement of He-ion implanted layer of W using transient thermoreflectance technique [J].Journal of Nuclear Materials,2017,484:382.
[11] Liu X,Lian Y Y,Greuner H,Boeswirth B,Jin Y Z.Irradiation effects of hydrogen and helium plasma on different grade tungsten materials [J].Nuclear Materials and Energy,2017,12:1314.
[12] Powell R W,Touloukian Y S.Thermal-conductivities of elements [J].Science,1973,181(4104):999.
[13] Lhuillier P E,Belhabib T,Desgardin P,Courtois B,Sauvage T,Barthe M F,Thomann A L,Brault P,Tessier Y.Trapping and release of helium in tungsten [J].Journal of Nuclear Materials,2011,416:13.
[14] Hussey N E,Takenaka,K,Takagi H.Universality of the Mott-Ioffe-Regel limit in metals [J].Philosophical Magazine,2004,84(27):2847.
[15] Fu B Q,Lai W S,Yuan Y,Xu H Y,Liu W.Calculation and analysis of lattice thermal conductivity in tungsten by molecular dynamics [J].Journal of Nuclear Materials,2012,427:268.
[16] Hu L,Wirth B D,Maroudas D.Thermal conductivity of tungsten:effects of plasma-related structural defects from molecular-dynamics simulations [J].Applied Physics Letters,2017,111(8):81902.
[17] Zhou X,Liu X H,Zhang D D,Shen Z J,Liu W.Balling phenomena in selective laser melted tungsten [J].Journal of Materials Processing Technology,2015,222:33.
[18] Dechaumphai E,Barton J L,Tesmer J R,Moon J,Wang Y.Near-surface thermal characterization of plasma facing components using the 3-omega method [J].Journal of Nuclear Materials,2014,455:56.
[19] Armstrong D E J,Edmondson P D,Roberts S G.Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten [J].Applied Physics Letter,2013,102(25):251901.