Comparison of Additively Manufactured and Cast Aluminum A205 Alloy

The relationships between the microstructure and thermal behaviour of additively manufactured and cast aluminum A205, a recently developed Al–Cu–Mg–Ag–TiB₂ alloy_, were investigated. Microstructural characterization performed using scanning electron microscopy (SEM) indicated a significant difference in grain size between laser powder bed fusion (LPBF) and cast specimens. Ultrafine round intercellular precipitates were observed in the LPBF structure, while intergranular precipitates were found in the cast structure. Trans-cellular TiB₂ particles were observed in the LPBF structure, while accumulated intergranular TiB₂ particles were found in the cast structure. Moreover, X-ray diffraction analysis revealed a higher fraction of precipitates in the LPBF specimen compared to the cast specimen. This was attributed to extremely high cooling rates which extend the solubility of alloying elements in the matrix. The thermo-analytical study demonstrated a strong correlation between the microstructural scale and precipitate dissolution kinetics of A205. The higher diffusion rate inherent in refined microstructures facilitates the dissolution of precipitates in the LPBF A205.