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

Mechanical properties of nanocrystalline materials

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

There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.

/pdf/effects-of-particle-size-particle-matrix-interface-adhesion-yv055zq7xi.pdf

Effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites

Below 1000°C the oxidation of nickel cannot be controlled by the diffusion of ions through the bulk crystal lattice of the pure oxide, because the measured oxidation rates are several orders of magnitude faster than would be predicted on this basis. Short-circuit diffusion through oxide grain boundaries or dislocations has usually been held responsible, but there has hitherto been no proper quantitative confirmation of this mechanism. We report measurements of the oxide scale thickness and oxide grain size as a function of time during the oxidation of high-purity nickel in the temperature range 500–800°C. All the oxidation experiments were carried out in pure oxygen at a pressure of one atmosphere. The measured parabolic oxidation rate constants have been compared with those calculated from grain boundary diffusion data obtained in our previous work, using a grain boundary diffusion model for the oxidation process. The quantitative agreement between measured and calculated oxidation rates shows c...

A quantitative demonstration of the grain boundary diffusion mechanism for the oxidation of metals

The ductility and bendability of AA5754 automotive sheets have been investigated as a function of iron content. The influence of pre-strain, introduced by cold rolling, on the bendability has also been examined. The low iron containing alloy (0.08 wt.%) showed development of surface instability in the form of small undulations on the tensile surface. In contrast, the high iron containing alloy (0.30 wt.%) showed cracks on the tensile surface. The development of damage during bending has been studied by carrying out in-situ bend tests in a scanning electron microscope. High iron containing alloy exhibits damage at the iron rich particles which leads to drastic reduction in the bendability.

Tensile and bending properties of AA5754 aluminum alloys

Critical grain size for dislocation storage and consequences for strain hardening of nanocrystalline materials

The role of structural defects in the growth of nickel oxide films

The ductility and bendability of the AA6111 aluminum alloy have been investigated as a function of iron content ranging from 0.06 to 0.68 wt.%. A significant decrease in ductility (as measured by the reduction of area at fracture) is observed as the iron level increases. Both the low and high iron-containing alloys fail in a shear mode due to void sheeting. The low iron alloy can be bent fully, although it develops significant grooves on the tensile surface linked to shear bands. The high iron alloy, however, develops cracks, running parallel to the bend axis. Both shear bands and cracks propagate along lines of maximum shear, i.e. close to 45° to the maximum tensile direction. These processes are closely linked. Observations suggest that this material is damage-sensitive such that once voids nucleate in shear bands they rapidly develop shear cracks that propagate through a void sheeting process. This results in a significant loss of both tensile ductility (as defined by the reduction of area) and bendability with increasing Fe content.

Tensile properties and bendability of T4 treated AA6111 aluminum alloys

The tensile properties, at both room and elevated temperatures, of laminated thin films containing alternate layers of aluminium and aluminium oxide were investigated. At room temperature the strength of the films followed a Hall-Petch type relationship dependent on the interlamellar spacing, and the strength could be extrapolated from data for conventional grain size aluminium. At the finest interlayer spacing of 50 nm, the strength was equivalent toμ/70, whereμ is the shear strength of aluminium and the samples exhibited very extensive ductility. At elevated temperatures, cavitation became an important deformation mechanism but it occurred preferentially at Al/Al rather than Al/Al2O3 boundaries. The microstructure of the films was probed using transmission electron microscopy and fractography was used to investigate deformation and fracture mechanisms.

J.D. Embury

Papers

Tensile and bending properties of AA5754 aluminum alloys

Critical grain size for dislocation storage and consequences for strain hardening of nanocrystalline materials

The role of structural defects in the growth of nickel oxide films

Tensile properties and bendability of T4 treated AA6111 aluminum alloys

The mechanical properties of laminated microscale composites of Al/Al2O3