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Serial sectioning technique provides plenty of quantitative geometric information of the microstructure analyzed, including those unavailable from stereology with one- and two-dimensional probes. This may be why it used to be and is being continuously served as one of the most common and invaluable methods to study the size and the size distribution, the topology and the distribution of topology parameters, and even the shape of three-dimensional space filling grains or cells. On the other hand, requiring tedious lab work, the method is also very time and energy consuming, most often only less than one hundred grains per sample were sampled and measured in almost all reported practice. Thus, a question is often asked: for typical microstructures in engineering materials, are so many grains or cells sampled adequate to obtain reliable results from this technique? To answer this question, experimental data of 1292 contiguous austenite grains in a low-carbon steel specimen obtained from the serial sectioning analysis are presented in this paper, which demonstrates the effect of sampling on the measurement of various parameters of grain size distribution and of the grain topology distribution. The result provides one of rules of thumb for grain stereology of similar microstructures.

Precious metal artefacts are characterized by a wide compositional nature and have been produced via different complex manufacturing techniques that have greatly influenced their chemical and metallurgical stability. Furthermore, the Ag or Au based alloys can be characterized by different amount of impurities coming from the extractive processes, which can influence their long-term mechanical and chemical properties. In this work, we try to specify the types of corrosion attack on the silver metal alloys surface in soil. Silver based alloys with chemical composition and metallurgical features similar to those of ancient alloys have been prepared in the laboratory. Coin-like coupons were artificially preaged and then submitted to soil corrosion conditions to simulate the corrosion patina of real artefacts before excavation. An extensive study of the produced patina layers was performed by Glancing Angle X-ray Diffractometry (GAXRD), Scanning Electron Microscopy (SEM) and EDS surface analysis as well as optical microscopy. The silver coupon examination shows the same type of attack as the one reported on original artefacts. © 2009 by NACE International.

The formation and stabilization of reversed austenite upon inter-critical annealing was investigated in a X4CrNiMo16-5-1 (EN 1.4418) supermartensitic stainless steel by means of scanning electron microscopy, electron backscatter-diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy and dilatometry. The results were supported by thermodynamics and kinetics models, and hardness measurements. Isothermal annealing for 2 h in the temperature range of 475 to 650 °C led to gradual softening of the material which was related to tempering of martensite and the steady increase of the reversed austenite phase fraction. Annealing at higher temperatures led to a gradual increase in hardness which was caused by formation of fresh martensite from reversed austenite. It was demonstrated that stabilization of reversed austenite is primarily based on chemical stabilization by partitioning, consistent with modeling results.

The ability to characterize the microstructure of a polycrystalline material is of utmost importance for materialsscience, because it enables to draw conclusions on its behaviour in a given application. The grain size is one of the key microstructure characteristics, which influences the physical and mechanical properties of a polycrystalline material. Electron backscatter diffraction, a state of the art technique used to accurately determine the material microstructure characteristics, is expensive, time-consuming and not available at every material science laboratory. For these reasons, the scientists often have to cope with small amount of data in their investigations. To overcome the lack in data availability, other tools, like focused ion beam and scanning acoustic microscopy, are commonly used to visualize a material's grain structure or fatigue induced degradation. However, these tools provide only visual output, which means that the resulting images need to be analyzed in order to get quantitative information necessary for further analyses. For this reason, in this work, an image analysis workflow to extract the microstructure characteristics such as damage patterns and grain size measurements out of different types of microstructure images is developed.The work is divided in three main tasks: detection of damage patterns, grain segmentation and image fusion. Since no training data was provided, unsupervised methods are used and implemented for answering these three research questions. The developed algorithms are integrated into a single framework that enables to quantify the microstructure characteristics of interest based only on scanning electron microscopy images.The effectiveness of the proposed workflow is evaluated by comparing the results with the corresponding data resulting from electron backscatter diffraction tool. The evaluations show that the proposed methodology is applicable in practice and provides robust and reliable results., Dženana Alagic, Dissertation Alpen-Adria-Universität Klagenfurt 2021