Advanced Metallographic Preparation of Advanced Alloys: Automation, Controlled Etching, and Correlative Validation

Advanced structural materials such as stainless steels, advanced high-strength steels, and nickel-based alloys often present significant challenges in metallographic preparation. Complex multiphase microstructures and high chemical stability frequently result in unstable etching response, insufficient phase discrimination, and reduced reliability when conventional manual procedures are applied. Improving confidence in metallographic characterization therefore benefits from more controlled and systematic preparation strategies.

This contribution presents selected approaches aimed at improving contrast stability through structured preparation workflows and automation-assisted procedures. Particular emphasis is placed on robot-assisted electrolytic etching, enabling controlled immersion time, sample movement, agitation, and electrical parameters. Modern electrolytic etchants with broad applicability are shown to provide consistent contrast development in duplex and austenitic steels as well as in nickel-based alloys, particularly where manual chemical immersion may produce variable outcomes.

Complementary color etching and heat tinting techniques are applied in tailored variants to enhance phase differentiation beyond conventional grayscale intensity contrast. The influence of selected preparation parameters on contrast formation is illustrated through representative case studies.

To assess preparation quality and support phase interpretation, a correlative microscopy workflow is employed. Identical regions of interest are examined using LOM and SEM (SE/BSE imaging) supported by EDS and EBSD. Observing the same microstructural features using complementary techniques enables a broader interpretation of phase distribution, morphology, and compositional variations, while reducing the likelihood of misinterpretation associated with single-modality analysis.

In addition, selected data-informed approaches are explored to support workflow optimization and multimodal interpretation. These include experimental image-to-image correlation between optical and electron microscopy data, systematic calibration of optical systems, and standardized image processing routines aimed at minimizing vignetting and optical artefacts.

Overall, the presented approaches indicate that combining controlled preparation, automation assistance, correlative validation, and calibrated imaging workflows can contribute to more robust metallographic characterization of advanced alloys in research and industrial contexts.