Metallic materials for 3D printing. Three-dimensional (3D) printing of metallic materials involves the consolidation of feedstock materials in the form of powder, wire, or sheet using various energy sources to form complex shapes. The past two decades have seen significant advances in the field in terms of both materials and technologies for metal 3D printing. The cover shows an additively manufactured nickel-based superalloy component, which was 3D-printed at Oak Ridge National Laboratory, demonstrating the ability to print on-demand metallic microstructures to target tailored properties. The component is a bracket meant for aerospace use. The two insets are electron backscatter images depicting the difference in texture between the two regions. The one on the left is a columnar grained material, and the one on the right is an equiaxed microstructure. See the technical theme that begins on page 729.