Research Projects

Metal matrix composites (MMCs) have emerged as promising materials for a wide range of advanced engineering applications across sectors such as aerospace, defense, biomedical, and nuclear industries, owing to their superior mechanical properties, thermal stability, and functional performance. However, conventional fabrication techniques, including powder metallurgy, liquid metal infiltration, and stir casting, suffer from several limitations. These include restricted geometric complexity, challenges in processing scalability, limited control over reinforcement distribution and orientation, high cost of raw powder materials, and the energy-intensive nature of the processes. To overcome these limitations, the present study proposes the use of Additive Manufacturing (AM), specifically within the Direct Energy Deposition (DED) domain, which fabricates layer-by-layer geometrically complex components with localized material control. Among various DED methods, the Wire Arc Additive Manufacturing (WAAM) process is selected due to its high deposition rates, lower operational costs, and industrial scalability, making it particularly suitable for medium to large-scale structural applications. While WAAM is well-established for monolithic metallic structures, its application in metal composite fabrication remains underexplored. This study aims to bridge that gap by developing a WAAM-based process capable of synthesising reinforced composites with enhanced microstructural control and property gradients. The initial phase will focus on process development, including feedstock integration, melt pool control, and reinforcement incorporation strategies, to enable the successful fabrication of high-performance metal matrix composites. One of the primary limitations in fabricating metal matrix composites (MMCs) via the WAAM process lies in the simultaneous and efficient incorporation of both wire (matrix material) and powder (reinforcement material) into the melt pool. The introduction of reinforcement particles presents several challenges, including spattering, inadequate wettability, low catchment efficiency, high melting points of ceramic reinforcements, and complications associated with off-axis powder feeding. To mitigate these challenges, a custom-designed coaxial nozzle shall be developed to enable synchronized feeding of both wire and powder directly into the melt pool. This coaxial configuration significantly improves powder catchment efficiency and enhances melt pool stability by minimizing directional inconsistency and thermal fluctuation during deposition. Two variants of the nozzle are proposed to be designed: one facilitating continuous powder feeding and the other enabling discrete multi-material injection to support functionally graded composite fabrication. The continuous-feed design features three symmetrically placed powder inlets at 120° intervals, each equipped with a dedicated intake for shielding gas (to protect the melt pool), carrier gas (for powder transport), and shaping gas (to stabilize melt pool geometry). Conversely, the discrete-feed design integrates six powder inlets, three dedicated to each of two different reinforcement materials, allowing for spatial modulation of composition to induce anisotropy or tailored property gradients in the deposited structure. Optimization of both coaxial-nozzle designs will be guided by computational fluid dynamics (CFD) simulations, accounting for key process parameters such as standoff distance, gas flow dynamics, reinforcement powder properties, etc. The proposed coaxial nozzle system represents a critical step forward in WAAM-based composite fabrication, offering enhanced control over reinforcement delivery, microstructural uniformity, and compositional grading essential for high-performance components.