Microstructure design of copper-based pseudoalloys using powder bed fusion and selective powder raking

• Applicant: Dr.-Ing. Zongwen Fu
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 569149068

Pseudoalloys are a special class of metal-metal composites composed of various components that are immiscible in the solid state. In pseudoalloys, different fractions, sizes and morphologies of the dispersed phases result in unique mechanical and physical properties. To produce pseudoalloys with nanoscale inclusions, the metallic components, which are miscible as liquids at high temperatures but not in the solid state, are melted together and quenched, so that the melt mixture is supercooled into the miscibility gap, leading to binodal or spinodal demixing as well as different microstructural morphologies.For pseudoalloys, the initial material composition and the cooling rate after melting play a crucial role in the type of demixing and the resulting microstructure morphologies. Additive Manufacturing (AM) based on powder bed fusion (PBF) using laser or electron beam, which simultaneously allows extremely high local processing temperatures and quenching rates, is predestined for tailoring the desired ultrafine microstructure of pseudoalloys. In addition, the recently developed selective powder raking approach for PBF allows control of the chemical composition in each individual layer during the AM process. Based on the selective powder raking method in combination with scan parameter optimization during PBF, the local microstructure properties with droplet-shaped or interpenetrating morphologies can be tailored in a targeted manner under the consideration of the influence of the initial composition and the cooling rate. In addition, the selective powder raking method enables producing functionally graded materials with desired microstructural properties, showing unique physical and mechanical properties.The aim of this research project is to gain a fundamental understanding of the correlation between the temperature history during PBF, the demixing mechanism and the resulting microstructural properties.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Bilal Gökce