Wire-influenced particle dynamics and fluid flow behaviors of melt pool in coaxial wire-powder fed directed energy deposition of metal matrix composites

Compared to the powder/wire-fed directed energy deposition (DED), wire-powder-fed DED (WP-DED) can offset the shortcomings of single filler injection and improve the comprehensive performance of as-built parts. In addition, WP-DED facilitates the effective production of metal matrix composites (MMCs) by changing wire and powder feed rates. WP-DED demonstrates a more intricate physical variation due to different material properties, additional wire-particle interactions, and complex heat transfer behaviors. However, the studies on the laser-filler-melt pool interaction behaviors in this process remain unexplored. In this work, SiC-reinforced Stainless Steel (SS) 316L MMC parts are fabricated through coaxial wire-powder fed DED (CWP-DED) with high manufacturing flexibility and uniform filler melting. In particular, a coupled discrete element method (DEM) and computational fluid dynamics (CFD) numerical model is advanced to understand the in-flight filler dynamics and fluid flow behaviors within the melt pool. The predicted results are validated by experimental data quantified by a high-speed optical imaging system and thermal imager. This research aims to deepen understanding of CWP-DED mechanisms for broader MMC applications in manufacturing.