| 摘要 |
A method of free form fabrication of metallic components, typically using computer aided design data, comprises selective laser binding and transient liquid sintering of blended powders. The powder blend includes a base metal alloy, a lower melting temperature alloy, and a polymer binder that constitutes approximately 5-15% of the total blend. A preform part is built up, layer-by-layer, by localized laser melting of the polymer constituent, which rapidly resolidifies to bind the metal particles. The binder is eliminated from the preform part by heating in a vacuum furnace at low atmospheric pressure. The preform part may require support during elimination of the polymer binder and subsequent densification by controlled heat treatment. Densification is performed at a temperature above the melting point of the lower temperature alloy but below the melting point of the base metal alloy to produce transient liquid sintering of the part to near full density with desired shape and dimensional tolerances. The densified part may be subjected to a final hot isostatic pressing (HIP) treatment to close residual porosity and complete the chemical homogenization of the part. Elimination of residual porosity improves fatigue properties of part, and homogenization improves ambient temperature ductility, toughness, and high temperature strength. An advantage of the process is rapid production of complex shaped metal prototypes and complete small batch production runs of high cost metal components without special tooling or machining operations.
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