Volume 53, Issue 7

Electron Backscatter Diffraction (EBSD) is a sensitive method to analyze samples with regard to their surface deformation condition. Hence, a possibly planar cross section without edge rounding as well as a best possible sample preparation are essential for the examination of edge areas up to the edge. Both objectives are quite contrary to each other, so that a comprehensive examination is important. Using Differential Interference Contrast (DIC) and Confocal Laser Scanning Microscopy (CLSM) and taking the example of soft pure iron, it was examined how different grinding media as well as mounting resins affect the cross section. The preparation quality was quantified by means of the EBSD Image Quality (IQ). The findings obtained were applied to the preparation of harder, technologically more relevant ferrous materials. It could be evidenced that the preparation using epoxy resin in combination with hardness regulator is a feasible method which meets both requirements.

As a result of their outstanding properties hard metals offer great potential in the tool industry. They are however expensive and geometrically limited when manufactured using conventional machining techniques. Additive manufacturing has the possibility to revolutionise the manufacture of such tools. The composition of hard metals consisting of a hard component within a binder phase in combination with laser based additive manufacturing can produce particular effects in the microstructural development of such materials. This article describes those particular microstructural developments which can be achieved in the powder metallurgical additive manufacturing of hard metals.

Internal interfaces are known to play a key role for the performance of thermoelectric materials. In the present work, structures with high interface densities consisting of alternating Bi 2 Te 3 and In 2 Te 3 layers with varying thickness and distance have been generated by two processes. First In 2 Te 3 was precipitated from a supersaturated Bi 2 Te 3 matrix. Second, layered structures were generated by directional solidification of hypoeutectic and eutectic alloys, demonstrating the variability of structures with high interface densities and anisotropy that can be generated by up-to-date solidification and phase transformation techniques. The resulting microstructures have a high potential to reduce the thermal conductivity while retaining a high electric conductivity.

This paper aims to examine the connection between the material quality with regard to the size and spatial distribution of the defects and the size or position of the defects causing the fracture which determine the durability of components in the range of Very High Cycle Fatigue (VHCF). For this purpose, the quality of the metastable austenitic steel 1.4301 was characterized via metallographic examinations. Longitudinal and cross sections were taken from a sheet steel. Afterwards size and position of all defects were measured. The metallographic information acquired was used to create a statistical defect distribution model. On the basis of this model and the stress distribution in the most stressed area of the used fatigue samples, the distribution of size and position of the inclusions relevant for the fatigue failure could be predicted. The results of the modelling are in good agreement with the experimental observations regarding the positions of crack initiation on samples failing under VHCF circumstances.

In this study, a Co-24Cr-8W–3Mo alloy (weight-%) is examined as cast and after hot isostatic pressing in a scanning electron microscope to identify the occurring phases through electron backscatter diffraction and energy dispersive X-ray spectroscopy. Tint etching and heat tinting were used to make the phases distinguishable even in the light microscope and thus be able to quantitatively evaluate the phase fractions without electron microscopy. The impact of hot isostatic pressing was examined in terms of phase fractions, the single phases' chemical composition and macroscopic hardness.