다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

http://www.uniroma2.it/didattica/tbs2/deposito/Manufacture,_characterisation_and_application_of_cellular_metals_and_metal_foams.pdf

Manufacture, characterisation and application of cellular metals and metal foams

The chemical, physical, and mechanical characteristics of nickel-based superalloys are reviewed with emphasis on the use of this class of materials within turbine engines. The role of major and minor alloying additions in multicomponent commercial cast and wrought superalloys is discussed. Microstructural stability and phases observed during processing and in subsequent elevated-temperature service are summarized. Processing paths and recent advances in processing are addressed. Mechanical properties and deformation mechanisms are reviewed, including tensile properties, creep, fatigue, and cyclic crack growth. I. Introduction N ICKEL-BASED superalloys are an unusual class of metallic materials with an exceptional combination of hightemperature strength, toughness, and resistance to degradation in corrosive or oxidizing environments. These materials are widely used in aircraft and power-generation turbines, rocket engines, and other challenging environments, including nuclear power and chemical processing plants. Intensive alloy and process development activities during the past few decades have resulted in alloys that can tolerate average temperatures of 1050 ◦ C with occasional excursions (or local hot spots near airfoil tips) to temperatures as high as 1200 ◦ C, 1 which is approximately 90% of the melting point of the material. The underlying aspects of microstructure and composition that result in these exceptional properties are briefly reviewed here. Major classes of superalloys that are utilized in gas-turbine engines and the corresponding processes for their production are outlined along with characteristic mechanical and physical properties.

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Nickel-Based Superalloys for Advanced Turbine Engines: Chemistry, Microstructure and Properties

Sluggish diffusion in Co-Cr-Fe-Mn-Ni high-entropy alloys

An experimental investigation into the strain rate sensitivity of a closed-cell aluminum foam at room temperature and under compression loading is conducted. The nominal strain rates are varied by four orders of magnitude, from 3.33×10−5 to 1.6×10−1 s−1. Within this range, experimental results show that the plastic strength and the energy absorbed increase (by 31 and 52.5%, respectively) with increasing strain rate. However, the plastic strength was found to increase bilinearly with the logarithm of strain rate, whereas dense metals tend to show only a linear response. As is the case with dense metals, the strain rate sensitivity of the foam was not a constant value, but found to be dependent on the strain and incremental change in strain rate. These results are explained with the aid of suitable micromechanical models such as microinertial effects against the bucking of cell walls at high strain rates that are unique to foams.

Strain rate sensitivity of a closed-cell aluminum foam

Variability in mechanical properties of a metal foam

Thermodynamics, phases and phase diagrams.- Structure of Materials.- Fick's laws of diffusion.- Development of interdiffusion zone in different systems.- Atomic mechanism of diffusion.- Interdiffusion and the Kirkendall effect in binary systems.- Growth of phases with narrow homogeneity range and line compounds by interdiffusion.- Microstructural evolution of the diffusion zone.- Interdiffusion in multicomponent systems.- Short circuit diffusion.- Reactive phase formation in thin film systems.

Thermodynamics, Diffusion and the Kirkendall Effect in Solids

The Kirkendall effect in multiphase diffusion

The tracer diffusion coefficients of the elements as well as the integrated interdiffusion coefficients are determined for the Cu3Sn and Cu6Sn5 intermetallic compounds using incremental diffusion couples and Kirkendall marker shift measurements. The activation energies are determined for the former between 498 K and 623 K (225 °C and 350 °C) and for the latter between 423 K and 473 K (150 °C and 200 °C). Sn is found to be a slightly faster diffuser in Cu6Sn5, and Cu is found to be the faster diffuser in Cu3Sn. The results from the incremental couples are used to predict the behavior of a Cu/Sn couple where simultaneous growth of both intermetallics occurs. The waviness at the Cu3Sn/Cu6Sn5 interface and possible reasons for not finding Kirkendall markers in both intermetallics in the Cu/Sn couple are discussed.

Aloke Paul

Papers

Strain rate sensitivity of a closed-cell aluminum foam

Variability in mechanical properties of a metal foam

Thermodynamics, Diffusion and the Kirkendall Effect in Solids

The Kirkendall effect in multiphase diffusion

Diffusion Parameters and Growth Mechanism of Phases in the Cu-Sn System