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J Kirschner, R. Gaschl, C. Eisenmenger-Sittner, J. Bernardi, C. Simson:
"Systematic Investigation of the Impact of Pure Metal Addition on AlCuMgZn Multi Principal Element Alloys";
Vortrag: ICMCTF 2021, San Diego/USA; 26.04.2021 - 30.04.2021.

Keywords: Magnetron-Sputtering, Multi-Principal Element Alloys, Crystallography, Light Metal Alloys

The design and synthesis of new materials and alloys is a crucial element in various technical areas, from the design of more energy-efficient mobility solutions to the construction of mechanically more robust alloys. Multi-Principal Element Alloys (MPEAs) show great potential as previous studies have shown that certain quaternary and quinary alloys containing approximately equal amounts of their constituents were superior to conventional alloys. The prediction of compatible elements and their optimal composition, especially in the area of light metals, represents a major challenge in this field and up to date, there is a lack of reliable models and concepts.

Multi-component layers (thickness of 10 µm) were co-deposited by magnetron sputtering and thereafter thermally treated to reveal the complex correlation between chemical composition, crystallography, mechanical properties and morphology. Quaternary systems including the elements Al, Mg, Zn and Cu were chosen to prepare samples in different compositions on a single substrate. Special emphasis was given to the increase of the relative Cu content with approximately the same ratios of the other alloying materials. Scanning electron microscopy in combination with energy dispersive X-ray spectroscopy and X-ray diffraction showed that the addition and increase of Cu have immense effects on the crystallographic phase formation. A wide concentration range in the Cu rich regime was observed (Cu content > 65 at%), in which a single phase system was formed. This range is characterized by significant indentation hardness variations and changes in microstructure. The obtained results were compared with the effects of the quantitative variation of the other constituents to evaluate the impact of different metals and metal classes (alkaline earth metals, transition metals, post-transition metals) on the system properties. Furthermore, the effects of the addition of a 5th element on the structure and crystallography of the alloy were investigated. These results establish a better understanding of the correlation between different metals in a complex system and expand the concept of high entropy alloys to the class of light metals to develop low density alloys. They should also provide valuable information for alloy synthesis using traditional methods such as melt synthesis.

Acknowledgements
This project has received funding by the Austrian Research Promotion Agency (FFG): Project PL2N_A, Grant No 865011