Metals are one of the most widely used types of engineering materials. Some of their properties, e.g. elastic constants, can be directly related to the nature of the metallic bonds between the atoms. On the other hand, macro- and microstructural features of metals, such as point defects, dislocations, grain boundaries, and second phase particles, control their yield, flow, and fracture stress. Images of microstructural elements can be obtained by modern imaging techniques. Modern computer aided methods can be further used to obtain a quantitative description of these microstructures. These methods take advantage of the progress made in recent years in the field of image processing, mathematical morphology and quantitative stereology. Quantitative description of the microstructures are used for modeling processes taking place under the action of applied load at a given temperature and test (service) environment. These model considerations can be illustrated on the example of an austenitic stainless steel, which is an important material for power generating and chemical industry. Reports recently published also show that properties of materials can be significantly modified by the effect of free surface. Examples of such situations include environmental effect on the mechanical properties of materials. Data for an austenitic stainless steel is used to discuss contribution of the free surface to the mechanical properties of metals.
Ultrafine-grained structure with grain size of about 100 nm was obtained in nickel by deformation under a pressure of 7 GPa in Bridgman anvils. The structure evolution in ultrafine-grained nickel was studied by residual resistance, transmission electron microscopy, X-ray diffraction, and microhardness measurements. It was established that the evolution of the structure upon heating of ultrafine-grained nickel may be divided into three stages. Stage A corresponds to temperatures below 453 K and is characterised by an insignificant decrease in the resistivity and microhardness. At this stage, a decrease in the internal stresses is not accompanied by grain growth. Stage B, corresponding to the temperatures range of 453-513 K, is characterised by an abrupt decrease in the resistivity and hardness, disappearance of the internal stresses, and by an intense grain growth. Stage C (above 523 K) corresponds to an insignificant increase in the resistivity and further decrease in the hardness.
We investigated three lunar regolith powder samples from the Apollo missions. Apollo 11 and Apollo 12 samples come from lunar maria and Apollo 16 sample from a highland region. In the present paper we summarise in brief results of measurements using photoelectron spectroscopy (XPS), micro-Raman spectroscopy (RM), x-ray diffraction (XRD), x-ray fluorescence spectroscopy (XRF), temperature programmed reduction and oxidation (TPRO), thermogravimetry (TG), differential thermal analysis (DTA) and nitrogen adsorption. Parts of samples are visualised by means of scanning electron microscopy (SEM/EDX) and atomic force microscopy (AFM).
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