POWDER AND WIRE-FED DIRECTED ENERGY DEPOSITION OF MONOLITHIC AND BIMETALLIC STRUCTURES OF 17-4PH, 316L SS, AND TITANIUM, AND METAL-MATRIX COMPOSITES OF AL4043-B4C FOR STRUCTURAL AND BIOMEDICAL APPLICATIONS

Aruntapan Dash

doi:10.7273/000007855

With a vision to harmonize strength with compliance, conductivity with biocompatibility, and fabrication freedom with metallurgical control, this work reimagines manufacturing as an intelligent choreography of materials. The study begins by grounding the evolution of additive manufacturing (AM) in its roots, from prototyping to a dynamic enabler of multifunctional systems. The first chapter provides a comprehensive overview of multi-material additive manufacturing (MM-AM), detailing the scientific and technological foundations that support the integration of polymers, metals, and ceramics within a single geometry. This foundation sets the tone for the innovations that follow, positioning MM-AM as a gateway to the next generation of adaptive, application-specific designs. The second chapter propels this vision into the biomedical domain by exploring 17-4 PH stainless steel as a superior alternative to conventional SS316L in fracture management devices. Employing laser-directed energy deposition (L-DED), the study reveals that magnetically stimulated 17-4 PH not only delivers over 150% higher compressive strength but also enhances osteoblast proliferation and suppresses bacterial colonization by up to 70%. This dual functionality, mechanical robustness, and bioactivity mark a critical stride toward infection-resistant, healing-enhancing implants. Chapter Three addresses the long-standing paradox in structural design: balancing strength and ductility, two properties that are often in conflict. This research pioneers the fabrication of bimetallic structures by integrating non-magnetic, ductile SS316L, which has limited strength, with magnetic, martensitic 17-4 PH, possessing higher strength but reduced ductility. Using powder-based L-DED, both vertical and radial constructs were crafted, including a unique radial architecture with an SS316L core encased in 17-4 PH. These structures displayed smooth interfacial grain transitions and optimized property gradients, demonstrating that compositional architecture can resolve material trade-offs within a single unified build. Chapter four shifts focus to the arc-based realm with a novel exploration of commercially pure titanium (CPTi) manufactured via WA-DED using a localized shielding system. This innovation enables large-scale, open-environment deposition without the degradation effects of oxidation. The resultant structures exhibit refined acicular α-grains, a preferred (002) crystallographic texture, and significantly reduced residual stress post-heat treatment, showcasing a pathway for scalable, cost-effective titanium part fabrication. In chapter five, the dissertation addresses the long-standing metallurgical incompatibility between CPTi and SS316L through an inventive interlayer strategy using CuSi-A filler wire. The hybrid WA-DED approach, combined with localized high-purity argon shielding, suppresses brittle Ti–Fe intermetallics and enables ductile bonding. The successful realization of a functionally graded auger screw prototype, combining a CPTi shell with an SS316L core, demonstrates the industrial viability of this technique for aerospace and biomedical components. The final chapter culminates in the fabrication of Al4043–B₄C metal matrix composites using a custom hybrid WA-DED platform. By integrating spatially controlled powder delivery with a cold metal transfer arc system, this process enables in situ ceramic reinforcement and overcomes energy-related limitations of conventional AM. The introduction of B₄C leads to significant grain refinement, controlled melt pool behavior, and porosity reduction, establishing a blueprint for structural-grade aluminum composites. Collectively, this dissertation does not merely advance multi-material additive manufacturing—it elevates it. By orchestrating a hybrid of energy sources and feedstocks, it redefines how dissimilar materials can be spatially co-engineered to meet diverse mechanical, functional, and biological demands. These insights chart a new course for AM: one where material becomes message, and manufacturing becomes multidimensional.

POWDER AND WIRE-FED DIRECTED ENERGY DEPOSITION OF MONOLITHIC AND BIMETALLIC STRUCTURES OF 17-4PH, 316L SS, AND TITANIUM, AND METAL-MATRIX COMPOSITES OF AL4043-B4C FOR STRUCTURAL AND BIOMEDICAL APPLICATIONS

Files and links (1)

Abstract

Metrics

Details