[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The application of automated Electron Backscatter Diffraction (EBSD) in the scanning electron microscope, to the quantitative analysis of grain and subgrain structures is discussed and compared with conventional methods of quantitative metallography. It is shown that the technique has reached a state of maturity such that linescans and maps can routinely be obtained and analysed using commercially available equipment and that EBSD in a Field Emission SEM (FEGSEM) allows quantitative analysis of grain/subgrains as small as ∼0.2 μm. EBSD can often give more accurate measurements of grain and subgrain size than conventional imaging methods, often in comparable times. Subgrain/cell measurements may be made more easily than in the TEM although the limited angular resolution of EBSD may be problematic in some cases. Additional information available from EBSD and not from conventional microscopy, gives a new dimension to quantitative metallography. Texture and its correlation with grain or subgrain size, shape and position are readily measured. Boundary misorientations, which are readily obtainable from EBSD, enable the distribution of boundary types to be determined and CSL boundaries can be identified and measured. The spatial distribution of Stored Energy in a sample and the amount of Recrystallization may also be measured by EBSD methods.

Review Grain and subgrain characterisation by electron backscatter diffraction

Fundamentals of Modern Manufacturing: Materials, Processes and Systems

Microstructurally inhomogeneous composites: Is a homogeneous reinforcement distribution optimal?

http://www.research.manchester.ac.uk/portal/files/48462559/PaperWithFigures.pdf

XCT Analysis of the Influence of Melt Strategies on Defect Population in Ti-6Al-4V Components Manufactured by Selective Electron Beam Melting

Precipitation of NbC in a model austenitic steel

In physical metallurgy it is frequently necessary to obtain quantitative measurements of microstructural features to compare experimental observations with theoretical; predictions. These may relate to the kinetics of processes such as grain growth, phase; transformations or particle coarsening, or to the development of mechanical properties; such as strength and toughness. Quantitative metallography, or stereology, is concerned with the measurement of microstructural features such as grain size, and the size and spatial distribution of second phase particles from observations made on sections by optical or scanning electron microscopy, and on replicas or thin foils by transmission electron microscopy. In all cases only a small sample section or thin slice of material is observed in order to dervie the microstructural characteristics in the bulk material. Stereology is therefore concerned with geometrical probability. The mathematics behind the analysis of experimental data has been developed over a long period from the middle of the nineteenth century. The aim of this book is to show examples of the application of these principles to calculate mean values and the confidence intervals for a number of important microstructural features. Knowledge of the accuracy of the experimental values of the microstructural parameters is essential for their valid interpretation and application. It is assumed that the reader is familiar with the application of statistical methods to data analysis, but the essentials are summarised in the Appendix.

Worked Examples in Quantitative Metallography

Interpenetrating composites consist of three-dimensionally interpenetrating matrices of two different phases; in the present work they were alumina and aluminium–magnesium alloys and were produced by infiltrating ceramic foams with molten alloys. The foams were made by mechanically agitating ceramic suspensions to entrain gases and then setting the structure via the in-situ polymerisation of organic monomers, a process known as gel casting. This resulted in the foams having a very open and interconnected structure that could be easily infiltrated by the molten metals. Previous composites have been produced at Loughborough University using squeeze casting; however, whilst infiltration was usually accomplished in a matter of seconds, the resulting size and shape of the composite was limited. Hence the present work has focused on investigating the potential for using gravity-fed infiltration. Whilst this was much slower, often taking several minutes, when optimised it is believed it will offer the potential for the production of large and complex-shaped pieces. The composites were produced at atmospheric pressure by infiltrating 2–10 wt.% magnesium content Al–Mg alloys into 20% dense Al 2 O 3 foams with highly interconnected porosity. The processing parameters of temperature, ≥900 °C, and atmosphere, flowing N 2 –Ar, were investigated to determine the processing window and infiltration kinetics. In-situ observation of the process shows that infiltration is faster at higher temperatures, Mg contents and N 2 partial pressures. Both optical and scanning electron microscopy (SEM) have been used to characterise the composites.

Rebecca L. Higginson

Papers

Precipitation of NbC in a model austenitic steel

Worked Examples in Quantitative Metallography

Processing of ceramic-metal interpenetrating composites

Complex precipitation behaviour in a microalloyed plate steel

An investigation into the use of electron back scattered diffraction to measure recrystallised fraction