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M.Sc. Parham Gemagami
Lehrstuhl Werkstoffwissenschaft
Institut für Werkstoffe
Fakultät für Maschinenbau
Ruhr-Universität Bochum
Universitätsstr. 150
44780 Bochum

Gebäude ZGH, Ebene 01, Raum 131
Activities: Research Assistant
Parham Gemagami is working under the DFG priority program 2006 on compositionally complex alloys (CCAs) and high-entropy alloys (HEAs). These alloys are multicomponent materials with interesting properties that continue to attract interest due to their wide compositional tuneability. Despite their promising properties for potential high-temperature applications, little is known about their thermal stability. It is well known from the field of high-temperature materials that, when alloys are subjected to long-term anneals at intermediate temperatures, intermetallic compounds may precipitate and degrade their mechanical performance and eventually their corrosion resistance (e.g., when the intermetallics are enriched in key elements for corrosion resistance such as Cr). Besides, since microstructural coarsening at elevated temperatures is detrimental to mechanical properties, it is important to evaluate the susceptibility of HEAs and CCAs with fine-scale microstructures to this phenomenon in order to assess their suitability for high-temperature applications.

In this context, Parham Gemagami investigates two types of alloys in his project, which is carried out in the new research center for interface-dominated high-performance materials (ZGH). The first is the equiatomic TiZrNbHfTa HEA, which forms a single-phase and disordered body-centered cubic (BCC) solid solution above 1200°C. The second is the Al0.7CrFeCoNi CCA with small additions of other elements (Mo, Ti, C), which is multiphase with a fine-scale lamellar microstructure in the as-cast state. Parham Gemagami anneals these alloys at various temperatures up to 1200°C for durations between 1 h and 1000 h. He analyses their microstructures using scanning and transmission electron microscopy to provide a comprehensive understanding of precipitation/coarsening kinetics in these alloys and establish temperature-time transformation (TTT) diagrams. The annealed materials are finally systematically characterized by tensile and hardness testing to uncover the relationships between microstructure and mechanical properties.

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