Interface Engineering and Scalability in PrintCast Metal-Matrix Composites

Abstract

PrintCast composites involve the infiltration of an additively manufactured mesh structure preform by a lower melting material. This technique has been demonstrated for a SS316L lattice structure fabricated by laser powder bed fusion (LPBF) with subsequent squeeze casting of A380 aluminum alloy with the purpose of reinforcing the strength of the Al-matrix while maintaining good thermal conductivity. Previous work successfully transitioned these interpenetrating phase composites from laboratory proof-of-concepts to large-scale 9 in × 6 in × 1 in (227 mm× 152 mm × 25 mm) panels using high-pressure die casting (HPDC). One of the successes in using HPDC is good metallurgical bonding was observed between the steel and Al-alloy matrix, with no noticeable gaps as previously observed in laboratory scale concepts. However, the bonding at the Al-Fe interface was so strong that tensile loading showed high strengths, but low ductility; inspection of the fracture surfaces found cracking in the Al-matrix, but not at the interface. The current study investigates methodologies for tailoring the Al-Fe interface that encourages interfacial sliding to restore system ductility and manage load transfer. Both Psot-preocessing heat treatment and a pre-infiltration concept are evaluated, including specialized AM printing strategies to alter surface topography. These surface modifications aim to control the intermetallic layer formation during the casting process, thereby facilitating controlled interface sliding to enhance global energy absorption and ductility. These preliminary results show promise in providing a framework for scaling highly engineered, locally reinforced hybrid structures for demanding structural and shielding applications.