Powder Casting: Producing Bulk Metal Components from Powder Without Compaction

Abstract

Powder casting was developed to produce metal components with near-theoretical density from low-cost, loose powder using hydrogen sintering and phase transformation. This has significant implications for non-beam metal additive manufacturing processes (e.g., metal extrusion AM, binder jetting, and ordered powder lithography), which produce green parts with relatively low densities. Additionally, powder casting can enable the production of geometries typically not suitable for powder processing, such as plate and bar stock. In the current study, Ti-6Al-4V, Zr, and Hf were densified to 99.2%, 95.7%, and 94.0% of their respective theoretical densities, when sintered from loose powder at 1200°C for 4 h. The relative density and pore size distributions of Ti-6Al-4V produced by powder casting were very similar to those produced by press-and-sinter HSPT.The powder-cast Ti-6Al-4V samples also displayed ductility consistent with press-and-sinter HSPT. However, they exhibited lower strength due to unintentional overheating during the dehydrogenation step.