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The coupling effects of low asymmetry of HCP structure and transient non-uniform stress/strain states during multi-pass deformation processing cause a great variation in crystallographic orientation of titanium tubes, which may induce anisotropic/asymmetrical behaviors and affect the formability and service performance of the materials. The unique plastic deformation and mechanisms under 3D stress need to be accurately and fully understood for integrated design of fabrication and forming of titanium tubular products achieving shape forming and property tailoring simultaneously. How to address this eluded and tantalized issue, however, is still a bottleneck issue. In tandem with this, taking high strength titanium tube (HSTT) as a case, by using macro/meso scaled hybrid methodology, a correlation among loading condition, distorted plasticity and texture evolution of the material is established and articulated: 1) Via Knoop indentation, tension/compression and EBSD, the distorted plasticity of HSTT is identified, and the coupling of three slip and two twinning modes are found to dominate the inhomogeneous deformation, which must be introduced in viscoplastic self-consistent (VPSC) crystal plasticity; 2) A compression-based orthogonal inverse method is used to calibrate the crystal plasticity parameters and validated from various aspects, and the VPSC-based computation is conducted for tubular materials with six typical initial textures under six fundamental loadings; 3) The remarkable distorted plasticity and evolution in strain hardening, strain flow and yield loci are observed for most cases; The interactions among slipping/slipping, slipping/twinning and twinning/twinning coordinate the anisotropic/asymmetrical behaviors and hence induce the distorted evolution of plasticity; The relationship between deformation modes (strain vectors) and texture evolution is constructed, and the tubes with the desired textures and bespoke properties can be tailored in cold rolling by allocating spatial plastic flow.

The new hemispherical photomultiplier tubes (PMTs) with 9 inch diameter from Hainan Zhanchuang Photonics Technology Co.,Ltd (HZC) have been studied. Narrow transit time spread (FWHM=2.35 ns) accompanied by small nonlinearity (750 photoelectrons at 5%) and high gain (1E7 ) with good single photoelectron (PE) resolution have been observed. 11 PMTs of this type are deployed and studied in the prototype detector for JUNO at IHEP, China., Comment: 9pages, 13 figures

This paper deals with elasto-plastic coupling solutions for the prediction of displacements around circular openings in elasto-brittle-plastic rock mass subject to hydrostatic stress. Both linear Mohr–Coulomb criterion and nonlinear Hoek–Brown criterion on the basis of a non-associated flow rule are considered. The restrictive condition between strength parameters and Young’s modulus in post-failure region for rock materials is theoretically established. Meanwhile, the proposed restrictive condition is validated by FLAC3D code that the advanced elasto-plastic coupling model (EPCM) based on Mohr–Coulomb criterion is merged in. Finally, the elasto-plastic coupling dimensionless displacements of circular opening in elasto-brittle-plastic rock mass are analyzed with different deterioration degree of Young’s modulus using two kinds of rocks. The results show that the deformation of rock mass increases obviously with the decrease of Young’s modulus in the plastic region, but Young’s modulus has little influence on the plastic region radius and stresses distribution form.

The inorganic crystals have been widely used for dark matter direct searching for many decades. However, limited by the crystal growth technique, a lot of small crystals have to be used together for large target mass, which results in a degradation of light collection efficiency. An experiment was built up to study the degradation, and the method of soaking crystals into mineral oil to improve the efficiency as well as reduce the interface effect were proposed and validated. Good data and MC agreements were achieved in the experiment.

The objective of this study is to interpret experimentally observed surface cracking and pitting caused by cyclic sliding contact. In our model, the fracture of two surface-breaking cracks in a homogeneous half plane is analyzed using the finite element technique. The half plane is loaded by a sliding rigid cylinder, which models a moving asperity. Stress intensity factors for the two crack tips are computed for complete loading cycles, and are used to analyze propagation of the two cracks. The maximum tensile stress criterion is adopted to predict crack propagation. It is shown that surface-breaking cracks have mutual shielding effects, resulting in decreases in stress intensity factors at the crack tips. The shielding effects increase with lowered inter-crack distance. The variation of shielding effects with crack spacing provides an explanation for the observed uniform spacing of surface cracks, while the effects of K I and K II stress intensity factors on crack propagation directions explain formation of surface pits.

High-resolution electron microscope (HREM) and computer simulation are used to investigate structural features of gold clusters produced by the inert-gas condensation method. The results indicate that (i) smaller clusters have multiple-twinned-like structure while those larger than 150 Å in diameter show single-crystal structure; (ii) the former cluster consists of either decahedral or icosahedral form and the atomic planes are not strictly parallel and distances between the planes increase towards the cluster edge; and (iii) grain boundaries between the clusters have twin structures with both long- and short-range orders.

Due to lead-free pressure, Sn-Ag-Cu solder is regarded as the potential substitute. However, higher melting point and faintish soldering restrict its wide application. Metal or rare earth metal doping can improve its soldering. In this thesis, effects of Zn, Ge metal doping on electrochemical corrosion behavior of lead-free Sn-3.0Ag-0.5Cu (SAC) solder in 3.5wt.% NaCl solution were investigated by potentiodynamic polarization. The electrochemical migration(ECM)attributed to dendrites growth were employed by the salt immersion experiment under direct current electrical field, and the oxidation characteristic was researched by thermo gravimetric analysis(TGA). The surface morphology and elemental composition of various elements in the doped solder were determined by analyzing the corrosion product or dendrites formed on the specimen by SEM, EDAX, XRD techniques. The corrosion results showed that the dendrite growth can be accelerated after Zn doping comparing to Sn-3.0Ag-0.5Cu solder when Zn percent larger than 1%, the same function suitable to Ge doping when Ge percent less than 1%. The shapes of dendrites were completely different after Zn, Ge doping, the fore looked like as rose flowers, the latter looked like cabbage palm, all dendrites grown from different kind of material can be well differentiated by the help of their fractal dimension. EDAX and XRD results showed that the content on dendrites of 95(Sn-3.0Ag-0.5Cu)-3Zn-2Ge solder were only Sn. TGA result showed Ge doping can improve the anti-oxidation capacity of SAC solder, however, Zn caused to the contrary effect. Thus provides a good technical support to develop a new lead-free solder substituting for Sn-37Pb.

Characterisation techniques based on quantum well intermixing have recently emerged as novel and exploratory methods for developing high power laser diodes. In this paper, we demonstrate the application of Zn impurities induced quantum well intermixing techniques to the non-absorbing windows fabrication for the AlGaInP/GaInP active region red-light laser diodes. The experimental results demonstrate that the photoluminescence characterisation had a blue shift of 23 nm for the diffusion parameters of 540°C and 20 minutes, and the maximum output power from the light-current tests of the thereafter fabricated non-absorbing windows laser diodes were improved by 47% than the conventional LDs.

Structures and optical properties of embedded copper clusters have been studied by EXAFS and optical absorption. The experiments demonstrate that (1) the interatomic distances contract and mean coordination number decreases as the cluster size decreases. (2) Optical resonances are greatly enhanced at visible region. These may be due to quantum size effect of the clusters themselves and the influence by its surrounding medium.