Volume 58, Issue 7

The preparation of metallographic sections from soft metals such as pure copper constitutes a particular challenge: the high degree of ductility promotes the formation of preparation artifacts and complicates the preparation of homogeneous, low-deformation surfaces. A metallographic preparation routine is therefore presented which has proven effective for pure copper and which can also be applied to additionally soft annealed samples. The subsequent removal of fine crystalline deformation layers is discussed and different setups for electropolishing and its optimization are presented.

A comprehensive description of complex material structures may require characterization using different methods and observations across several scales. This work will present a correlative approach including light optical microscopy, scanning electron microscopy and electron backscatter diffraction, enabling microstructure quantification which combines microscopic images and electron backscatter diffraction data. The parameters obtained from electron backscatter diffraction such as misorientation parameters or grain and phase boundary data are an ideal source of information, complementing microscopic images. Two case studies performed on bainitic microstructures will be presented to demonstrate practical applications of this approach.

For the chemical and structural analysis of paint pigments from a historic “Frankfurt Kitchen”, a correlative approach was employed, using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy complemented by X-ray phase analysis. This paper will demonstrate how metallographic techniques can be used for issues beyond our traditional area of activity.

Fingerprints, a butterfly’s wings, or a lotus leaf: when it comes to surfaces, there is no such thing as coincidence in animated nature. Based on their surfaces, animals and plants control their wettability, their swimming resistance, their appearance, and much more. Evolution has optimized these surfaces and developed a microstructure that fits every need. It is all the more astonishing that, with regard to technical surfaces, man confines himself to random roughnesses or “smooth” surfaces. It is surely not a problem of a lack of incentives: structured surfaces have already provided evidence of optimizing friction and wear [1, 2, 3, 4], improving electrical contacts [5, 6], making implants biocompatible [7, 8], keeping away harmful bacteria [9], and much more. How come we continue counting on grinding, polishing, sandblasting, or etching? As so often, the problem can be found in economic cost effectiveness. It is possible to produce interesting structures such as those of the feather in Fig. 1. However, generating fine structures in the micro and nanometer range usually requires precise processing techniques. This is complex, time-consuming, and cannot readily be integrated into a manufacturing process. Things are different with Direct Laser Interference Patterning, DLIP) [10, 11]. This method makes use of the strong interference pattern of overlapped laser beams as a “stamp” to provide an entire surface area with dots, lines, or other patterns – in one shot. It thus saves time, allows for patterning speeds of up to 1 m 2 /min and does it without an elaborate pre- or post-treatment [10, 12]. The following article intends to outline how the method works, which structures can be generated, and how the complex multi-scale structures that nature developed over millions of years can be replicated in only one step.