Volume 56, Issue 2

We present how the conventional focused ion beam (FIB) lift-out method can be modified to obtain phase selective specimens for atom probe tomography (APT). The modified method combines selective deep etching with site-specific lift-out using a micromanipulator in a FIB/SEM workstation. This method is used for phase-selective sample preparation in alloys with complex microstructures such as the coral- and plate-like silicon structures in the eutectic phase of Al-Si castings. The method proves to be both, practical and robust, with a high success rate of high-quality phase-specific APT specimens.

Recent studies show that there are major variations in the mechanical properties of additively manufactured precipitation-hardenable AlSi10Mg samples. These variations are caused by the varying precipitation hardening condition which, in turn, can be attributed to dwell times varying at elevated temperatures. Another influence on the microstructure can be revealed when looking at the different building orientations. AlSi10Mg samples were manufactured with different building orientations in order to investigate this in greater detail. They were subjected to a hardness measurement and microstructural analysis. Different heat treatment options were studied and the additively manufactured AlSi10Mg samples were subsequently subjected to a homogenizing heat treatment. New hardness measurements and microstructural examinations were performed in order to document the successful homogenization process.

High alloy TRIP steels offer an excellent combination of strength and formability. The pronounced metastability of the γ austenite present in the material in its unstressed condition places high demands on the metallographic preparation of the section as it must ensure a low level of transformation, i. e. a low level of deformation. In addition, these steels contain phases with an identical lattice structure, i. e. the differentiation of the phases is made considerably more difficult when established methods for the phase analysis such as EBSD and XRD are used. In this work, a methodology for a preparation of polished sections offering a low level of transformation is developed and compared to conventional preparation methods. In this context, various phase analysis methods are compared. In addition, a possibility for a quantitative phase analysis of these multi-phase materials by combination of microscopic and radiographic methods is presented.