*Article* **Fractal Nature of Advanced Ni-Based Superalloys Solidified on Board the International Space Station**

**Vojislav Miti´c 1,2,\*, Cristina Serpa 3, Ivana Ili´c 4, Markus Mohr <sup>5</sup> and Hans-Jörg Fecht <sup>5</sup>**


**Abstract:** Materials science is highly significant in space program investigation, energy production and others. Therefore, designing, improving and predicting advanced material properties is a crucial necessity. The high temperature creep and corrosion resistance of Ni-based superalloys makes them important materials for turbine blades in aircraft engines and land-based power plants. The investment casting process of turbine blades is costly and time consuming, which makes process simulations a necessity. These simulations require fundamental models for the microstructure formation. In this paper, we present advanced analytical techniques in describing the microstructures obtained experimentally and analyzed on different sample's cross-sectional images. The samples have been processed on board the International Space Station using the MSL-EML device based on electromagnetic levitation principles. We applied several aspects of fractal analysis and obtained important results regarding fractals and Hausdorff dimensions related to the surface and structural characteristics of CMSX-10 samples. Using scanning electron microscopy (SEM), Zeiss LEO 1550, we analyzed the microstructure of samples solidified in space and successfully performed the fractal reconstruction of the sample's morphology. We extended the fractal analysis on the microscopic images based on samples solidified on earth and established new frontiers on the advanced structures prediction.

**Keywords:** Ni-based superalloys; international space station; microstructure; morphology; fractal reconstruction; Fractal Hausdorff dimension
