【摘要】 为了预测长期锂化壁处理工艺对第一壁材料——钨的影响,本工作采用第一性原理计算,探讨锂、氦杂质原子在金属钨中的行为及其对钨金属材料力学和热力学性质的影响。计算结果表明,单一锂原子在钨晶体中倾向于占据替代位置,该替代锂原子和位于间隙位置的氦或其他锂原子之间皆存在较强的正结合能,而且当多个间隙氦或锂原子聚集在替代锂原子周围时,体系仍然具有正结合能。对钨晶体含有锂或氦多原子聚集体力学性能(体弹模量、剪切模量、杨氏模量、泊松比、柯西压力)的计算结果表明,锂或氦多原子聚集体的出现将导致钨材料的力学强度降低,韧(展)性提高。采用准简谐Debye模型对含有锂或氦多原子聚集体的钨材料的吉布斯自由能、等容热容、熵等热力学性质的计算结果表明,锂或氦多原子聚集体的出现也将导致钨金属体系的热力学性质发生变化,这将对钨金属材料的温度分布、杂质浓度等产生一定的影响。更多还原

【Abstract】 In order to evaluate the effects of Li-coated process on the working performance of first-wall material,tungsten,first-principles calculations were performed to investigate the behaviors of lithium and helium impurity atoms in tungsten and their influences on the mechanical and thermodynamic properties of tungsten. The results show that an isolated lithium atom tends to occupy a substitutional site in tungsten,and there exist strong binding energies between the substitutional Li atom and the neighboring interstitial He atoms or Li atoms. From the results obtained in the calculations of bulk modulus,shear modulus,Young’s modulus,Poisson’s ratio,and Cauchy pressure,it is found that the presence of polyatomic lithium or helium aggregates gives rise to the reduction in mechanical strength and ductility improvement of tungsten. The calculated results of the thermodynamic properties on the basis of the quasi-harmonic Debye model indicates that the Gibbs free energy,heat capacity at constant volume and entropy of tungsten containing the polyatomic lithium or helium aggregates are changed in comparison with pure tungsten. The polyatomic lithium or helium aggregates could have a certain level of impact on the temperature distribution and impurity concentration etc. in tungsten.更多还原