84 research outputs found

    国际化十年:一家澳大利亚零售银行的经验之谈

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    上个世纪最后四十年见证了国际银行业务和跨国银行业务显著增长的历程。推动这一发展的力量包括全球化、解除管制以及信息技术的发展。在19世纪及20世纪初发生的第一次现代意义上的跨国银行业务发展浪潮中,那些来自殖民宗主国的银行领导了时代潮流。而在最近的这次跨国银行业务扩张中,美国的金融机构占据了领导地位,这是与第一次明显不同的。因此,许多学术文章都着重研究美国的银行,包括他们的动机、经营战略以及国际化经验。此外,与银行业国际化的第一阶段相比,此次银行业的国际化扩张更大程度地突出了批发和机构银行业务,而不是零售银行业务(除了少数例外)。这一特点在近年来对跨国银行经营的学术研究中也体现得十分明显[ 有关调查,见Bain,et al (2001)。]。译者单位:厦门大学经济学院国际经济与贸易系(361005

    Production of Novel Superelastic Biocompatible Ti-Nb-based Alloys for Medical Application

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    Vacuum induction melting (VIM) and vacuum arc remelting (VAR) methods were used to produce biocompatible Ti-Nb-based alloys. In case of VIM BeO was used as material of crucible, and copper mold cup in case of VAR. Superelastic biocompatible Ti-22Nb-3Ta-3Zr, Ti-22Nb-6Ta and Ti-22Nb-6Zr (at %) alloys were produced. Samples of obtained alloys were investigated by scanning electron microscopy with XRSMA. It was shown that bulk chemical compositions of all VAR alloys exactly corresponded to their nominal chemical compositions. Element distribution maps showed that there was significant chemical inhomogeneity in VIM samples. On the other hand, VAR samples had no such areas and all elements were distributed homogeneously

    Production of Novel Superelastic Biocompatible Ti-Nb-based Alloys for Medical Application

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    Vacuum induction melting (VIM) and vacuum arc remelting (VAR) methods were used to produce biocompatible Ti-Nb-based alloys. In case of VIM BeO was used as material of crucible, and copper mold cup in case of VAR. Superelastic biocompatible Ti-22Nb-3Ta-3Zr, Ti-22Nb-6Ta and Ti-22Nb-6Zr (at %) alloys were produced. Samples of obtained alloys were investigated by scanning electron microscopy with XRSMA. It was shown that bulk chemical compositions of all VAR alloys exactly corresponded to their nominal chemical compositions. Element distribution maps showed that there was significant chemical inhomogeneity in VIM samples. On the other hand, VAR samples had no such areas and all elements were distributed homogeneously

    Role of Nickel Content in One-Way and Two-Way Shape Recovery in Binary Ti-Ni Alloys

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    The shape recovery characteristics of titanium nickelide with an Ni content of 50.0 at % and 50.7 at % were studied in a wide range of structures obtained as a result of cold drawing with an accumulated true strain of e = 0.52 and subsequent annealing in the 250 to 700 °C temperature range. Shape memory effect (SME) inducing was carried out by bending using a non-isothermal loading mode, which made it possible to reveal implementing elastic strain in the equiatomic alloy up to 12% and thereby increase the total shape recovery by a factor of 1.5. The obtained results prove that the Ni content strongly affects the value and specific features of changes of the shape recovery characteristics with loading strain as well as grain/subgrain size. In equiatomic alloy, the total recovery strain manifests its maximum of 13.5–15% and the recovery strain of 9% at a loading strain range of 12 to 14%. In Ni-rich alloy, the total recovery strain manifests its maximum of 20% and the recovery strain of 14% at a loading strain range of 15 to 21%. The maximum two-way SME value correlates with the residual strain in both alloys and reaches its maximum of 3.0% in a material with a recrystallized structure. Varying the loading strain value under bending in the 11 to 21% range allows regulation of the temperature of shape recovery in Ni-rich alloy in the 45 to 80 °C range

    Novel Zr-Rich Alloys of Ternary Ti-Zr-Nb System with Large Superelastic Recovery Strain

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    Four novel superelastic alloys, Ti-41Zr-12Nb, Ti-42Zr-11Nb, Ti-43Zr-10Nb, Ti-44Zr-10Nb (at.%), were obtained and studied in terms of their microstructure and mechanical properties. The obtained alloys were subjected to thermomechanical treatment, providing alloys with a pronounced superelastic behavior. Materials phase composition and microstructure were studied using XRD and SEM methods. Based on the XRD results, maximum lattice strains in the 011β direction were calculated as 5.9%, 6.3%, 7.5%, and 7.2% for Ti-41Zr-12Nb, Ti-42Zr-11Nb, Ti-43Zr-10Nb, and Ti-44Zr-10Nb alloys, respectively. Mechanical properties of the thermomechanically-treated alloys were studied by Vickers microhardness testing, static tensile testing, and superelastic mechanical cycling. The maximum superelastic recovery strains attained at room temperature was 3.7%, 1.9%, 3.2%, and 3.0% for the Ti-41Zr-12Nb, Ti-42Zr-11Nb, Ti-43Zr-10Nb, and Ti-44Zr-10Nb alloys, respectively. Ti-41Zr-12Nb alloy demonstrated the highest ductility, with relative elongation to failure of over 20%, combined with the total recovery strain of more than 6%. Obtained results indicate that Ti-41Zr-12Nb is one the most promising alloys of the Ti-Zr-Nb system, with quite perfect superelastic behavior at room temperature

    Production, Mechanical and Functional Properties of Long-Length TiNiHf Rods with High-Temperature Shape Memory Effect

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    In the present work, the possibility of manufacturing long-length TiNiHf rods with a lowered Hf content and a high-temperature shape memory effect in the range of 120–160 °C was studied. Initial ingots with 1.5, 3.0 and 5.0 at.% Hf were obtained by electron beam melting in a copper water-cooled stream-type mold. The obtained ingots were rotary forged at the temperature of 950 °C, with the relative strain from 5 to 10% per one pass. The obtained results revealed that the ingots with 3.0 and 5.0 at.% Hf demonstrated insufficient technological plasticity, presumably because of the excess precipitation of (Ti,Hf)2Ni-type particles. The premature destruction of ingots during the deformation process does not allow obtaining high-quality long-length rods. A long-length rod with a diameter of 3.5 mm and a length of 870 mm was produced by rotary forging from the ingot with 1.5 at.% Hf. The obtained TiNiHf rod had relatively high values of mechanical properties (a dislocation yield stress σy of 800 MPa, ultimate tensile strength σB of 1000 MPa, and elongation to fracture δ of 24%), functional properties (a completely recoverable strain of 5%), and a required finishing temperature of shape recovery of 125 °C in the as-forged state and of 155 °C after post-deformation annealing at 550 °C for 2 h

    Structure and Properties of TiNi Shape Memory Alloy after Quasi-Continuous Equal-Channel Angular Pressing in Various Aged States

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    The effect of quasi-continuous (QC) equal-channel angular pressing (ECAP) in various pre-aged states on the structure formation and mechanical and functional properties of a hyper-equiatomic titanium nickelide (TiNi) shape memory alloy is studied. QC ECAP with a channel intersection angle of 110° is carried out at a temperature of 450 °C after aging for 1 and 5 h for three passes. To investigate the obtained structure and properties, the following research methods are applied: transmission electron microscopy, XRD analysis, calorimetric study, tension and hardness tests, and a special technique for the determination of functional properties. QC ECAP allows for the considerable refinement of structural elements and results in obtaining a mixed fine-grade structure, with structural elements of average sizes of 92 nm after pre-aging for 1 h and 115 nm after pre-aging for 5 h. Pre-aging for 5 h before QC ECAP, in combination with QC ECAP and post-deformation aging at 430 °C for 1 h, provides the best combination of mechanical and functional properties: a dislocation yield stress of 1410 MPa, ultimate tensile strength of 1562 MPa, and total recoverable strain of 11.6%. These values are comparable with the best results obtained for titanium nickelide and expand opportunities for the application of smart shape memory devices

    Dependence of Electrochemical Characteristics of a Biodegradable Fe-30Mn-5Si wt.% Alloy on Compressive Deformation in a Wide Temperature Range

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    Fe-30Mn-5Si alloy subjected to a compression test at various deformation temperatures ranging from 350 to 900 °C with a strain rate of 1 s−1 are studied. It was found that the Fe-30Mn-5Si alloy exhibits high resistance to the dynamic recrystallization process in a whole studied range of deformation temperatures. There are no differences in structure formation in the zone of action of tangential tensile stresses and peripheral and central zones of localized compressive stresses. The room-temperature X-ray diffraction study shows the presence of a single-phase state (FCC γ-austenite) after deformation temperature range from 350 to 700 °C and a two-phase state (FCC γ-austenite + HCP ε-martensite) after deformation test at 900 °C. The presence of a two-phase state provides a higher rate of biodegradation compared with a single-phase state. The changes in the biodegradation rate dependence on the structure change with an increase in the deformation temperature are explained. Favorable temperature regimes for subsequent thermomechanical processing are proposed based on the relationship between structure formation and biodegradation rate to obtain semi-products from the Fe-30Mn-5Si alloy
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