Development and innovations of modern high-performance materials rely crucially on the repertoire of characterization methods available. While individual techniques provide information on a specific aspect of the investigated material, a comprehensive understanding requires a correlative approach in which complementary information are needed from exactly the same Region of Interest (RoI). Therefore, correlative methodologies combining several techniques are indispensable in a wide range of scientific disciplines including materials science [1].

In contrast to the traditional EDX and EELS spectroscopies, SIMS is well-known for high-sensitivity (ppm), high dynamic range and more interestingly, isotope analysis for all the elements of the periodic table. This presentation will highlight the benefits of correlating SIMS imaging with complementary analysis using Electron Back Scattered Diffraction (EBSD) and Atomic Force Microscopy (AFM). As the SIMS images do not reveal crystallographic orientations of the grains in the microstructure, studies that aim to correlate structural defects such as twinning and grain boundary orientation in a multiphase material require that the strengths of SIMS are coupled with that of EBSD to probe the local crystallographic characteristics. As a first step, we correlate the SIMS with EBSD imaging to complement specific chemical characteristics seen in SIMS with the corresponding crystallographic characteristic captured in EBSD.

To further characterize the material and for correct interpretation, the exact topography of the RoI is required. We do topographic analysis using an AFM on the exact location where SIMS and EBSD analysis are carried out. In this way, a three-way correlative methodology is developed. As each of these analyses is done on separate instruments, specific methodological strategies are employed to overcome the challenges.

To illustrate this methodology, we selected the topic of hydrogen embrittlement in a TWinning Induced Plasticity (TWIP) steel [2]. As conventional techniques such as EDX are not capable of mapping hydrogen distribution, the SIMS approach brings a particularly strong advantage to this study. Prior to the SIMS analysis, the steel samples were electrochemically charged with deuterium to distinguish it from hydrogen naturally present in the sample. The SIMS images of H^– and D^– distributions are obtained from a Cameca NanoSIMS50 with a Cs⁺ primary ion beam. Then, EBSD and AFM analyses are carried out on the exact location to correlate SIMS chemical characteristics with crystallographic defects such as twins, grain boundaries and sample topography.

In this presentation, we will introduce and demonstrate this correlative paradigm for materials characterization. We will also present the scientific and technical challenges and discuss the strategies to go beyond the current state-of-the-art.

References:

T. Wirtz et al, Nanotechnology, Vol. 26, 434001, 2015.

L. Mosecker et al, Mat. Sci. Engr. A, 642, p71-85, 2015.

Acknowledgments: This work was co-funded by the Luxembourg National Research Fund (FNR) by the grant C13/MS/5951975.

Figures:

Figure 1: (A) SIMS ratio image of D/H maps, (B) EBSD inverse pole-figure map of the same RoI, (C) SIMS-AFM overlay to correlate SIMS ratio image with topography and (D) EBSD-AFM overlay to correlate crystallographic details with topography. The z axis in C and D is in nm.

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