Analysis of the crystallographic anisotropy of the lattice strains, i.e. the analysis of the dependence of the lattice strain on the crystallographic direction, is discussed to be an efficient method for getting information about the mesoscopic local strains and microscopic local strain fields in dual‐phase materials. This technique is illustrated on the example of hot‐rolled pearlitic steels containing ferritic lamellae separated by cementite from each other. In these samples, the information about the local strain fields was further used to build a microstructure model that describes the interaction between crystallites of different phases on the microscopic scale. Such a microstructure model is quite appropriate for examination of the correlations between the structure and properties of the pearlitic steels, because it links the microstructure parameters obtained using X‐ray diffraction on the atomic level with the interaction between the crystallites or grains of different phases, which can more directly be related to the macroscopic mechanical properties of the materials. The second important result of this study was the detection and explanation of several correlations between individual microstructure parameters, which are obtained from X‐ray diffraction. This offers a possibility to use the X‐ray diffraction for a fast microstructure analysis of pearlitic steels, or generally for a fast microstructure analysis of dual‐phase steels, after or even during the rolling processes.

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In principle, the plasma nitriding of Al based substrates is a well-known process, though it remains extremely challenging from both the technological point of view and the aspect of stress loading conditions. In order to improve the latter, a duplex treatment consisting of plasma nitriding and subsequent surface remelting using electron beam technology was employed. The focus of this paper (part I) was on the characterisation of the initial microstructure after plasma nitriding. This should create the basis for a better understanding of the processes taking place or changes in the subsequent duplex treatment. This was done with the help of high-resolution imaging and analysis tools in the scanning and transmission electron microscope as well as XPS analyses. Special attention was paid to the nitriding mechanism at the interface as a function of the local microstructural constituents of the hypereutectic Al alloy substrate (Al solid solution, primary silicon, and intermetallic phases). While the main part of the nitride layer formed consisted of AlN and small fractions of pure Al in the diffusion paths, other nitrides and oxides could also be detected in the area of the interface.

Parts from a specially grown multicrystalline test ingot showed diffuse absorption regions in the IR transmission. The underlying defects were investigated with IR microscopy and FTIR spectroscopy. The typical features that can be observed in the IR microscope images of wafers from the diffuse absorption regions are long filament-like defects aligned in bundles and having a preferential orientation along the crystallization direction. In FTIR spectroscopy broad absorption bands in the wavenumber range between 750 and 1050 cm -1 can be found in specimens from the same diffuse absorption regions. EDS measurements with a scanning electron microscope yield an increased nitrogen concentration. It is thus suggested that the underlying defects are silicon nitride particles that can grow under certain growth conditions. The preferential orientation indicates that these rod-like defects grow at the liquid-solid interface from the melt during crystallization.

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