[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

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

J. Appl. Cryst.の発刊に際して

Dynamic and post-dynamic recrystallization under hot, cold and severe plastic deformation conditions

A review of dynamic recrystallization phenomena in metallic materials

The texture and microstructure evolutions of a fine-grained TWIP steel subjected to tensile tests at room temperature were investigated in relation to the mechanical behavior. This steel combines both high ductility and strength owing to the TWIP effect. Also the steel exhibits a high strain hardening rate that evolves according to five stages, which are related to the microstructure and texture evolutions and characteristics. The formation of nano-twins in the initial stage of deformation leads to an increase in strain hardening rate. The development of the pronounced fiber in the tensile direction sustains mechanical twinning and maintains the strain hardening rate on a high level. The resulting microstructure exhibits several types of twin configurations and sub-boundaries with high misorientations due to intense activities of dislocation glide. The twin volume fraction was estimated to be 9% at the final stage of tensile deformation. The new orientations generated by mechanical twinning do not change considerably the final texture.

/pdf/analysis-of-the-tensile-behavior-of-a-twip-steel-based-on-1otz1eu58g.pdf

Analysis of the tensile behavior of a TWIP steel based on the texture and microstructure evolutions

A 99.995% pure Ni sample, compressed to 25%, was annealed in a SEM chamber and changes in the density of annealing twins were monitored in situ during recrystallization and grain growth. In addition to average microstructural measurements, the evolution of individual grains was also observed. Both the average annealing twin density in the recrystallized domain and the annealing twin density per grain increased during recrystallization. The rate of increase in twin density correlates with the velocity of the recrystallization front. During grain growth, however, the average annealing twin density decreased. The in situ EBSD observations showed both the formation of new twins and the extension of existing twins during annealing. The observations reported here suggest that the existing models for annealing twin formation are incomplete.

/pdf/annealing-twin-development-during-recrystallization-and-ym96fh69g6.pdf

Annealing twin development during recrystallization and grain growth in pure nickel

Evolution of recrystallisation texture and microstructure in low alloyed titanium sheets

The aim of this work is to present a quantitative analysis of features involved in recovery during annealing of deformed Tantalum. In pure metals where crystalline defects usually have high mobility, dislocation annihilation and rearrangement occur to a great extent prior to recrystallization. Therefore a complete understanding of recrystallization cannot be accomplished without an advanced knowledge of the recovery phenomenon. Depending on whether dislocations induce a measurable curvature in the crystal lattice or not, they are called Geometrically Necessary Dislocations (GNDs) or Statistically Stored Dislocations (SSDs) respectively. In the present work only GNDs are considered. For this purpose electron backscatter diffraction (EBSD) is an advantageous technique to obtain statistically representative results when compared to Transmission Electron Microscopy (TEM). However, a quantitative analysis of GNDs from EBSD data is not straightforward. Since local misorientations are induced by the curvature of the crystal lattice caused by GNDs, GNDs analysis can be done using local misorientations. However the values obtained from this analysis are step size dependent and influenced by the measurement noise. Reasoning on the basis that when the step size tends to zero, local misorientation should also tend to zero, measurement noise can be estimated [1]. The measurement noise appears to notably be very much dependent on the amplitude of local misorientations, which must be considered in the perspective of GND density calculation

https://iopscience.iop.org/article/10.1088/1757-899X/89/1/012038/pdf

About quantitative EBSD analysis of deformation and recovery substructures in pure Tantalum

The evolutions of microstructure and crystallographic texture in low-alloyed titanium sheets are investigated by electron backscattering diffraction at different grain growth stages. Recrystallization of 80% cold-rolled sheets and subsequent grain growth lead to equiaxed microstructures. The texture obtained at the end of primary recrystallization is very close to that of the cold-rolled state, with the maximum value of the orientation distribution function at {0°, 35°, 0°}. The orientations developing during grain growth correspond to a broad peak centered around {0°, 35°, 30°} which is a minor component in the initial texture. The disappearing orientations are widely scattered throughout orientation space and present two major disadvantages in the growth competition: (i) they are highly misoriented with respect to the growing texture component and (ii) the grains having these orientations belong to the smallest size range in the microstructure obtained at the end of the primary recrystallization. The grain boundaries remaining after extended grain growth are characterized by an increasing proportion of misorientations below 30° and random rotation axes.

Nathalie Bozzolo

Papers

Analysis of the tensile behavior of a TWIP steel based on the texture and microstructure evolutions

Annealing twin development during recrystallization and grain growth in pure nickel

Evolution of recrystallisation texture and microstructure in low alloyed titanium sheets

About quantitative EBSD analysis of deformation and recovery substructures in pure Tantalum

Texture evolution during grain growth in recrystallized commercially-pure titanium