The behaviour of ternary compounds InGaAs and GaAsN subjected to electron irradiation

This paper presents results of the effect of electron beam irradiation under UHV conditions on InGaAs/GaAs and GaAsN/GaAs systems using Auger electron spectroscopy (AES) and the electron energy loss spectroscopy (EELS) as surface analytical techniques. The ternary compounds In_0.53Ga_0.47As and In_0.2Ga_0.8As were irradiated by an electron beam under identical conditions (5 KeV; 10⁻³ A cm⁻²; for 60 min). The results showed that the compound In_0.53Ga_0.47As was stable under electron irradiation whereas changes in the Auger signal In-M₄₅N₄₅N₄₅ revealed that the electron beam had a significant effect on the compound In_0.2Ga_0.8As. GaAsN growth at 590 °C on GaAs is believed to produce a surface containing defects that is chemically unstable when bombarded by electrons. It was found that heating this compound at 730 °C stabilised the surface, protecting it from the effect of electron irradiation.     

Radiation stability of ceramics: Test cases of zirconia and spinel

The study of the effects of radiation in ceramics of potential use in electronic, space and nuclear industries appears to be a major challenge in the next decades. The collect and analysis of data dealing with the production and recovery of radiation damage in this type of materials are thus tasks of prime interest. In this article, we present a review of the main structural and chemical modifications observed in test case ceramics (yttria-stabilized zirconia and magnesium-aluminate spinel) submitted to ion bombardment and thermal treatments. We show that the stability under irradiation depends on the intrinsic properties of the materials and on irradiation parameters such as the ion energy, fluence and temperature. We also demonstrate that the recovery of damage upon annealing at elevated temperatures induces drastic physico-chemical modifications of the matrix.     

石油钻机井架载荷谱的编制

载荷谱是进行机械结构强度试验和疲劳损伤研究的重要依据,而井架本身承受随时间变化的动载荷作用,加之各钻井工况承载变化不一,建立符合钻井实际的载荷时间历程成为进行瞬态分析和疲劳损伤研究的需要。通过实测钻机井架在钻探过程的大钩载荷,运用极值统计分析方法,建立最大载荷概率分布模型,运用疲劳载荷谱的编制方法,完成了井架正常钻探时的载荷时间历程的编制,并获得了可用于试验加载的程序载荷谱。编制的程序载荷谱包含了所有钻探作业工况,反映了井架真实承载环境,可用于钻机井架的瞬态分析和疲劳损伤研究,并大大简化了计算过程,提高了井架动力分析的可靠性。     

An accumulation damage model for fatigue fracture of ferroelectric ceramics

The accumulated plastic displacement criterion for crack propagation in traditional materials is extended to develop equations to predict the fatigue crack growth of ferroelectric ceramics subjected to combined electromechanical loads. The crack-line is perpendicular to the poling direction of the medium. An electric saturation zone and a stress saturation zone are assumed to develop at the crack tips when the medium is subjected to external electromechanical loads. This assumption makes it possible to obtain the accumulated plastic deformation in closed form. A fatigue crack growth law, which is a fourth-power function of the effective stress intensity factor, similar to the well-known Paris law, is derived. Graphical results for the effect of electric load on the effective crack tip stress intensity factor and crack growth rate are provided.     

Feature tests on welded components at higher temperatures—Material performance and residual stress evaluation

A reliable maintenance and service of energy generation plants would be impossible without the professional designing, manufacturing and monitoring of welded joints. The lifetime assessment factors of welded components as implemented in the design codes must be updated accounting for the modern materials and the advanced steam parameters used in the piping construction [Weld Strength for high temperature components design and operation (WELDON). European Project No. GRD2-2000-30363, Gampe U, Seliger P, Creep crack growth testing of P91 and P22 pipe bends. Int J Pressure Vessels Piping 2001;78:859-64, INTEGRITY of repair welds in high temperature plants operating under steady and cyclic loading conditions. European Project No. G5RD-CT-1999-00118].Within the EU 5th Framework RTD project ‘WELDON’ tests at high temperatures are performed on component-like feature test specimens like welded pipes and large tensiles in addition to laboratory specimens to study the geometry and size effects on the damage evaluation methodology. The circumferential welds of the pipes are subjected simultaneously to internal pressure and an axial load. The large tensile specimens manufactured from the welded pipes are subjected to uniaxial loading. These components are made from steel grade P22 and P91 and are equipped with gages for on-line monitoring of temperatures, deformations and strains.Residual stresses are measured on these components in as welded and after post-weld heat treatment (PWHT) conditions and are monitored during creep testing with interruptions and after failure. X-ray and hole drilling techniques are employed in these measurements. These data will be used to validate the FE modelling of residual stresses and damage assessment.The results obtained from long time creep tests, metallographic investigations of damage development in the different zones of the weldment and residual stress measurements are presented in this paper.     

智能混凝土损伤自修复全过程分析

混凝土及其结构能够自动适应环境，在受到损伤后能够自行修复，是解决结构中的混凝土损伤的最佳途径。利用内置内含修复胶粘剂的胶囊实现了混凝土损伤的自修复，一旦混凝土中出现损伤或裂缝，胶囊破裂，其中的修复胶粘剂流出，使其修复。通过有限元软件ANSYS，建立了混凝土有限元模型，对其损伤自修复全过程进行了计算分析，揭示了损伤自修复的机理。最后，通过试验验证了计算分析方法的正确性和合理性。     

Threshold voltage shift of submicron p-channel MOSFET due to Si surface damage from plasma etching process

We compared performances for transistors produced using both wet and dry etching for non-silicide processes in the CMOS technology. It was found that the dry process for non-silicide area induces the threshold voltage shifting of the pMOS transistor as well as increases the contact resistance on active region. Also, GIDL (gate-induced-drain-leakage) current has a poor junction leakage current compared with the wet etching process. Moreover, the dry etching process changes the doping profile of the P⁺ junction and the p-channel transistor region. The experiments showed the dry etching process generates the Si-SiO₂ interface trap site due to plasma-induced damage.     

Monte Carlo Simulation of Damage Depth in Focused Ion Beam Milling Si3N4 Thin Film

The damage properties of Focused Ion Beam（FIB） milling Si3N4 thin film are investigated by the detailed analyzing images of nanoholes and simulation of Monte Carlo. The damage depth in the Si3N4 thin film for two different ion species（Gallium and Arsenic） under various parameters（ion energy, angle of incidence） are investigated by Monte Carlo method. The simulations show the damage depth increases with the increasing ion energy, the damage depth is dependent on the angle of incident ion, the curves of the damage depth for Ga ion and As ion at 30 keV nearly superpose, while the damage depth for Ga with 90 keV ion is more than that for As ion with the same energy.     

Mg:Ce:Fe:LN晶体的生长及位相共轭分析

在Ce:Fe:LN中掺进不同摩尔分数(0,2%,4%,6%)的MgO首次以提拉法生长Mg:Ce:Fe:LN晶体,并对晶体进行极化、氧化和还原处理。测试晶体的吸收光谱和光损伤阈值。Mg:Ce:Fe:LN晶体吸收光谱吸收边相对Ce:Fe:LN晶体发生紫移。Mg:Ce:Fe:LN晶体光损伤阈值比Ce:Fe:LN晶体增大,研究了Mg:Ce:Fe:LN晶体吸收边移动机理和光损伤阈值增加机理。采用4波混频光路测试Mg:Ce:Fe:LN晶体位相共轭反射率和响应时间,Mg:Ce:Fe:LN晶体位相共轭反射率相对Ce:Fe:LN晶体降低,但响应速度增加。以x(Mg)2%(摩尔分数):Ce:Fe:LN晶体位相共轭镜消除信号光波的位相畸变。