Wire arc additive manufacturing: A review on quality enhancement using nano-particle reinforcement

Wire Arc Additive Manufacturing (WAAM) has emerged as a promising metal additive manufacturing technique due to its high deposition rate, cost-effectiveness, and ability to build large-scale components. However, challenges such as porosity, poor mechanical properties, limited microstructural control, and residual stress hinder its full potential. Incorporating nanoparticles into the WAAM process has recently gained significant attention as a strategy to enhance material performance. This review provides a detailed and systematic analysis of the various types of nanoparticles used in WAAM, their methods of incorporation, effects on microstructure, mechanical performance, and functional properties of the built components. This review provides the first comprehensive classification and quantitative analysis of nanoparticle incorporation strategies in WAAM, systematically categorising 72 research articles across four distinct deposition strategies, including feedstock modification, interlayer application, direct melt pool injection, and ultrasonic dispersion. This work presents a comparative framework analysing the relative efficacy of different nanoparticle types (carbides, nitrides, and oxides) across multiple alloy systems, revealing that TiC emerges as the most extensively studied reinforcement. The review establishes that nanoparticle addition demonstrates positive influence on yield strength and ultimate tensile strength up to optimal concentrations, beyond which agglomeration-induced property deterioration occurs. Furthermore, the review identifies future perspectives for the optimized integration of nanoparticles in WAAMfor high-performance manufacturing, design of multifunctional and hybrid reinforcement strategies, and adoption of AI-driven predictive modeling. The review discusses the industrial adoption barriers of the process. This systematic framework provides practical guidance for nanoparticle selection and process optimization, accelerating the industrial deployment of nanoparticle-reinforced WAAM technology.