Additive manufacturing of heterostructured metallic materials: Processing, microstructural characteristics, mechanical properties, and service performance

Developing high-performance metallic materials with excellent mechanical properties and reliable service performance is an everlasting objective of materials research. The perspective on heterostructured materials with dramatic differences in compositions and structures, in conjunction with advanced additive manufacturing methods, offers a spectrum of feasible strategies to artificially create high-performance metallic materials. Despite the extensive literature on heterostructured materials, there is a notable absence of a comprehensive review focusing on additively manufactured heterostructured materials, their process-structure-property relationships, and detailed deformation mechanisms. This review presents an overview of typical heterostructures in metallic materials, including layered, bonded, and gradient heterostructures. It examines the prevalent additive manufacturing methods used to fabricate various heterostructured metallic materials and discusses their compositional and structural characteristics, encompassing steels, titanium alloys, aluminum alloys, high-entropy alloys, multi-material parts, etc. Furthermore, it covers the effects of heterostructures on mechanical properties and service performances, such as hardness, fracture toughness, strength, ductility, fatigue, wear, and corrosion properties. The review elucidates how local compositional transformations, structural configurations, and distributions within the building domains of different types of heterostructures govern the overall deformation mechanisms. This, in turn, leads to the local optimization and enhancement of mechanical properties and produces unprecedented properties of heterostructured metallic materials.