Effects of oxygen concentration and irradiation defects on the oxidation corrosion of body-centered-cubic iron surfaces: A first-principles study

Oxidation corrosion of steels usually occurs in contact with the oxygen-contained environment, which is accelerated by high oxygen concentration and irradiation. The oxidation mechanism of steels is investigated by the adsorption/solution of oxygen atoms on/under body-centered-cubic (bcc) iron surfaces, and diffusion of oxygen atoms on the surface and in the near-surface region. Energetic results indicate that oxygen atoms prefer to adsorb at hollow and long-bridge positions on the Fe(100) and (110) surfaces, respectively. As the coverage of oxygen atoms increases, oxygen atoms would repel each other and gradually dissolve in the near-surface and bulk region. As vacancies exist, oxygen atoms are attracted by vacancies, especially in the near-surface and bulk region. Dynamic results indicate that the diffusion of O atoms on surfaces is easier than that into near-surface, which is affected by oxygen coverage and vacancies. Moreover, the effects of oxygen concentration and irradiation on oxygen density in the near-surface and bulk region are estimated by the McLean's model with a simple hypothesis.     

Corrosion related properties of iron(100) surface in liquid lead and bismuth environments:A first-principles study

The corrosion of steels in liquid metal lead （Pb） and bismuth （Bi） is a critical challenge in the development of accel-erator driven systems （ADS）. Using a first-principles method with a slab model, we theoretically investigate the interaction between the Pb （Bi） atom and the iron （Fe） （100） surface to assess the fundamental corrosion properties. Our investigation demonstrates that both Pb and Bi atoms favorably adsorb on the （100） surface. Such an adsorption decreases the energy required for the dissociation of an Fe atom from the surface, enhancing the dissolution tendency significantly. The seg- regation of six common alloying elements （Cr, A1, Mn, Ni, Nb, and Si） to the surface and their impacts on the corrosion properties are also considered. The present results reveal that Si seems to have a relatively good performance to stabilize the surface and alleviate the dissolving trend caused by Pb and Bi.     

S~(1/2)=200GeV质子对撞中横质量谱劈裂效应的PYTHIA模拟研究(英文)

在质心系能量为200GeV的质子-质子对撞中,高横质量区域产生的强子横质量谱分裂成两类——重子和介子．应用PYTHIA产生器进行Monte Carlo分析其内在的物理机制．模拟结果表明,这种劈裂效应不仅在弦碎裂模型中出现,而且独立碎裂模型中也有,并且在RHIC能区(200GeV)下主要来源于胶子的贡献．在PYTHIA6．3版本中引入的新的物理机制表明复杂的弦纠缠(string junction)形式可能是这种重子一介子差异的主要原因．     

√S=200GeV质子对撞中横质量谱劈裂效应的PYTHIA模拟研究

在质心系能量为200GeV的质子－质子对撞中, 高横质量区域产生的强子横质量谱分裂成两类——重子和介子. 应用PYTHIA产生器进行Monte Carlo分析其内在的物理机制. 模拟结果表明, 这种劈裂效应不仅在弦碎裂模型中出现, 而且独立碎裂模型中也有, 并且在RHIC能区(200GeV)下主要来源于胶子的贡献. 在PYTHIA6.3版本中引入的新的物理机制表明复杂的弦纠缠(string junction)形式可能是这种重子--介子差异的主要原因.