Material extrusion (MEX)-based additive manufacturing of metallic materials: review of current trends, challenges, and opportunities

Material extrusion (MEX)-based additive manufacturing (AM) has arisen as a versatile strategy for producing metallic and alloy components, integrating cost efficiency with design adaptability. This review offers an extensive evaluation of the MEX process, highlighting key components such as filament synthesis, 3D printing, debinding, and sintering, which collectively determine the quality and performance of the finished products. A thorough investigation of the microstructure-property correlation elucidates how process parameters influence density, mechanical characteristics, and the evolution of microstructure in materials processed via MEX. Progress in modeling frameworks is highlighted, showcasing their crucial role in enhancing material flow, thermal interactions, and densification processes to elevate the precision and consistency of the fabricated parts. Moreover, the review articulates quality assurance and monitoring methodologies, accentuating their critical role in guaranteeing defect-free components and sustaining uniformity throughout the production process. Despite its potential in aerospace, automotive, and biomedical applications, MEX-based AM faces challenges in achieving high-density components, minimising residual stresses, and scaling up for industrial adoption. The paper concludes by offering insights into future research directions, including the enhancement of advanced filaments, the development of real-time monitoring systems, and the refinement of predictive modeling tools, aimed at effectively leveraging the capabilities of MEX-based AM for metallic materials and alloys.