Turn Nonweldable Ni-Superalloys Printable and Microstructurally Controllable

Ni-based superalloys are critical materials in aerospace and power generation industries due to their exceptional high-temperature performance, achieved through carefully designed chemical compositions and meticulously controlled microstructures. Traditionally, these components are manufactured through subtractive processes that are costly and time-intensive, yet even these high-value components are prone to damage during prolonged service in harsh environments, necessitating innovative methods for manufacturing, remanufacturing, and repair. Recent advancements in 3D-printing technologies have demonstrated significant potential in addressing these needs, particularly for nonweldable Ni-based superalloys, but formidable challenges remain. Key issues include preventing crack formation, controlling crystal grain structure, and optimizing precipitate volume fraction and morphology to enhance mechanical properties. Here, an overview of the recent studies that have elucidated fundamental mechanisms underlying these challenges, such as elemental microsegregation, melt pool morphology, and the spatiotemporal distributions of microscopic defects and stresses, is presented. Based on these insights, strategies involving the optimization of printing parameters and the implementation of heat treatments are developed to improve the printability and microstructural controllability. By examining the fabrication of a turbine blade as an example, this review highlights the progress made, the persistent challenges, and future opportunities for the 3D printing of high-performance Ni-based superalloy components.