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31.
Microstructure evolution of zircaloy-4 during Ne ion irradiation and annealing: An in situ TEM investigation
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The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr(Fe, Cr)2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr(Fe, Cr)2 precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr(Fe, Cr)2. The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases. 相似文献
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为研制出满足惯性约束聚变(ICF)实验的氘氚(DT)冷冻靶, 需要控制DT结晶生长过程, 实现DT单晶生长, 由此减少影响冰层均匀化及聚变实验的晶体缺陷. 本文运用晶体生长形态动力学理论建立了密排六方晶体(hcp)单晶生长模型, 实验中通过对靶室进行± 3 mK精确控温, 采用可见光背光成像技术在线表征了低温下玻璃微球内氘(D2)的结晶生长过程, 结果表明: 在20–100 Pa低温氦气导热环境下, 通过缓慢降温可显著降低氘晶体生长过程中形成的缺陷; 当降温速率达到2 mK/min时, 观测到了氘燃料的两种单晶生长过程, 实验具有可重复性; 建立的hcp单晶生长理论模型与实验结果符合, 并与美国利弗莫尔国家实验室(LLNL)的DT单晶生长过程进行了对比, 提出了冷冻靶内D2/DT燃料的单晶生长方法. 相似文献
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根据设计,未来聚变堆等离子体排灰气中除了氘氚还含有以惰性气体为主的杂质气体,会在钯膜纯化氢同位素的过程中产生不容忽视的浓差极化现象,降低排灰气的处理效率。针对这一现象,以氢氦混合气为源项,研究了钯膜在分离氢氦过程中浓差极化对渗氢性能的影响,利用极化系数对浓差极化的程度进行评估,并考察了渗氢驱动力、氦气浓度以及原料气流量对极化系数的影响。结果表明:在150,300,450kPa时的H2/He选择性分别为37 460,18 347和7935,可以看出钯膜致密性良好;浓差极化系数随着渗氢驱动力和氦气浓度的升高而增大,对于原料气流量的变化则呈现相反趋势。 相似文献
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Microstructure and hardening effect of pure tungsten and ZrO2 strengthened tungsten under carbon ion irradiation at 700℃
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Chun-Yang Luo 《中国物理 B》2022,31(9):96102-096102
Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO2 alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation. Carbon ion irradiation is performed at 700 ℃ with irradiation damages ranging from 0.25 dpa to 2.0 dpa. The results show that the irradiation defect clusters are mainly in the form of dislocation loop. The size and density of dislocation loops increase with irradiation damages intensifying. The W-1.5%ZrO2 alloy has a smaller dislocation loop size than that of pure tungsten. It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO2 phase improves the sink strength for irradiation defects. It is confirmed that the W-1.5%ZrO2 alloy shows a smaller change in hardness than the pure tungsten after being irradiated. From the above results, we conclude that the addition of ZrO2 into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials. 相似文献
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本文采用第一性原理研究了六角相ErAx (A=H, He)的弹性性质, 其中x=0, 0.0313, 0.125, 0.25, 分别讨论了体系中不同浓度的氢和氦对体系弹性性质的影响. 计算结果表明, 六角相铒-氢体系晶体的弹性常数、体弹模量、剪切模量、杨氏模量基本上随着晶体中氢的浓度增加而增加, 然而, 铒-氦体系的弹性常数、体弹模量、剪切模量和杨氏模量几乎随着氦浓度的增加而降低. 从电荷转移方面分析了氢和氦与Er的相互作用, 发现六角相ErHx的弹性性质随H浓度的变化机理与ErHex随He浓度的变化机理不同.
关键词:
第一性原理
弹性性质
x')" href="#">六角相ErHx
x')" href="#">六角相ErHex 相似文献
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采用分子动力学模拟的方法,研究了LiCl-KCl-CeCl3熔盐中CeCl3的结构性质和热力学,获得了LiCl-KCl-CeCl3熔盐中密度与组成、密度与温度的关系数据;径向分布函数gCe-Cl(r)的第一个峰位置为0.259nm, Ce3+对应的第一个配位数约为6.9;混合熔盐中计算数据与纯熔盐中数据的差异可以解释为混合熔盐中Ce3+和Cl-的相互作用比纯的CeCl3更强; LiCl-KCl熔盐中Ce3+的自扩散活化能为22.5 kJ·mol-1,从活化能的本质来说, Ce3+自扩散所需要克服的能垒要略低于U3+(25.8 kJ·mol-1)。当Ce3+的摩尔分数从0.005增加到0.05时,其指前因子从31.9×10-5 cm2·s-1减少到21.8×10-5 cm2·s-1;随着Ce3+摩尔分数从0.005增长到0.05,单位体积内(忽略总体积的变化)Ce3+的增加意味着其扩散阻力增加,而自扩散的能力降低,导致了指前因子的减小。 相似文献
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The effects of substrate temperature on the microstructure and the morphology of erbium film are systematically investigated by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). All the erbium films are grown by the electron-beam vapor deposition (EBVD). A novel preparation method for observing the cross-section morphology of the erbium film is developed. The films deposited at 200 ℃ have (002) preferred orientation, and the films deposited at 450 ℃ have mixed (100) and (101) texture, which are due to the different growth mechanisms of surface energy minimization and recrystallization, respectively. The peak positions and the full widths at half maximum (FWHMs) of erbium diffraction lines (100), (002), and (101) shift towards higher angles and decrease with the increasing substrate temperature in a largely uniform manner, respectively. Also, the lattice constants decrease with the increasing temperature. The transition in the film stresses can be used to interpret the changes in peak positions, FWHMs, and lattice constants. The stress is compressive for the as-growth films, and is counteracted by the tensile stress formed during the process of temperature cooling down to room temperature. The tensile stress mainly originates from the difference in the coefficients of thermal expansion of substrate--film couple. 相似文献
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采用磁悬浮法制备了4种TiHfx,(x=0.13,0.26,0.52,1.03)二元合金。利用X射线衍射技术对纯钛、纯铪和4种成分Ti-Hf二元合金吸氘前后的物相结构、晶胞参数和吸氘特性进行了研究。Ti-Hf合金吸氘前均为六方密堆结构,饱和吸氘后形成较单一的面心四方ε相氘化物。随Hf含量增加,Ti-Hf合金及其ε相氘化物的晶胞参数均呈增大趋势。压强-组成等温线显示,Hf含量增加将导致氘化物室温平衡压升高,Ti-Hf合金热力学性质趋近于H-Hf体系,Hf对Ti-Hf合金氘化物热力学性质起主导作用。Hf掺杂显著降低了Ti吸氘的体膨胀,从而有望缓解由于体胀导致的氢脆现象。 相似文献