Multi-wire additive manufacturing: A comprehensive review on materials, microstructure, methodological advances, and applications

Abstract

The industrial demand for high-performance multi-material components is rapidly growing due to their superior functionality in advanced applications. Traditional Wire Arc Additive Manufacturing (WAAM) is typically limited to the use of a single wire, which possesses a specific chemical composition and results in fixed properties for the fabricated component. Multi-Wire Arc Additive Manufacturing (MWAAM) has emerged as a promising alternative due to its ability to achieve property variations at specific locations, along with its cost-effectiveness and flexibility. This review examines the advancements in MWAAM for multi-material fabrication. It aims to evaluate the microstructural and mechanical properties of components produced, identify research gaps, and propose strategies for future advancements. The review synthesises findings from studies published between 2015 and 2024, specifically focusing on MWAAM applications in fabricating functionally graded materials (FGMs), bimetallic structures (BMS), high-entropy alloys (HEAs), shape memory alloys (SMAs), and intermetallic compounds (IMCs). Factors such as wire feeding mechanisms, deposition strategies, microstructural evolution, and mechanical performance have been analysed. MWAAM demonstrates significant potential in fabricating advanced multi-material components with enhanced strength, thermal stability, and corrosion resistance. Its capabilities include precise composition control and the creation of gradient structures using advanced wire feeding systems, such as dual-wire and twin-wire configurations. However, MWAAM is challenged by microstructural heterogeneity, phase segregation, and prevalence of porosity and cracking. Addressing these challenges through computational modelling and real-time monitoring systems can lead to broadening its industrial adoption and impact.