Unraveling the Role of Annealing in Tailoring Structure and Performance of Additively Manufactured Metal Matrix Composites

Metal matrix composites (MMCs) are engineered materials consisting of a metal matrix reinforced with a secondary phase and exhibiting superior mechanical properties compared with monolithic metals. Additive Manufacturing (AM) has emerged as a promising approach for fabricating MMCs because it enables near-net-shape components in a single step, thereby reducing material waste, shortening lead time, and minimizing subtractive post-processing challenges associated with high-performance MMCs. However, the rapid heating and cooling inherent to fusion-based AM produce non-equilibrium structural states that lead to uncertainties in material properties. Annealing heat treatment provides a potential pathway to recover these non-equilibrium states. While annealing effects on AM-fabricated metallic components have been studied, corresponding investigations into AM-fabricated MMCs remain limited. This award supports research aiming to address this knowledge gap through a fundamental investigation of annealing-induced microstructural evolution, its effects on AM MMCs properties, and their underlying mechanisms. The outcomes will advance scientific understanding of the relationships among annealing conditions, microstructural evolution, and resulting properties, thus enabling improved control of AM MMCs behavior. This award is expected to benefit sectors such as aerospace, biomedical, and defense, where high-performance AM MMCs are increasingly important, thereby supporting national economy, health, and security.  Research enabled by this award investigates the effects of annealing on the microstructure and properties of AM MMCs. Regarding microstructural evolution, the research seeks to elucidate the dynamics of thermal misfit stress relaxation, reinforcement reprecipitation, dislocation recovery, sub-grain and grain evolution, and chemical redistribution during different annealing conditions through in-situ neutron diffraction during heating and transmission electron microscopy. Complementary kinetic and Eshelby-based modeling is used to uncover the underlying mechanisms governing these processes and establish a quantitative framework for predicting microstructural evolution during annealing. Regarding mechanical properties, the research aims to determine how annealing-induced microstructural evolution influences mechanical behavior and deformation mechanisms, including load sharing, matrix strengthening, strain hardening, and failure, through the integration of in-situ neutron diffraction during tensile testing with analytical modeling. If successful, this research project is expected to establish quantitative process-structure-property relationships that enable consistent control of microstructure and properties in AM MMCs through annealing. The resulting insights into thermally driven microstructural evolution will also advance understanding of the role of reinforcement in stabilizing MMCs for high-temperature applications. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2611685 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Minglei Qu | Institution: Arizona State University, SCOTTSDALE, AZ | Award Amount: $350,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2611685 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2611685.html