Development of heat treatments for additively manufactured alloys

Abstract

Additive Manufacturing using technologies such as Laser-based Powder Bed Fusion of metals (PBF-LB/M) holds great promise for the fabrication of complex, highly individualized or integrated components for aerospace applications and beyond. However, when it comes to demanding conditions such as faced for instance by high-temperature materials in propulsion systems, the materials’ properties have to be tailored to meet the requirements. Almost always the materials properties in the “as-printed” state that typically corresponds to a metastable microstructure can be improved by substantially by a proper heat treatment. Varying the postprocessing chain, the material can even be tuned to, e.g., high ductility, yield strength or other desired properties. At the German Aerospace Center, we investigate heat treatments for a variety of materials including aluminium and titanium alloys, titanium aluminides or nickelbase superalloys. Using characterization techniques such as, e.g., in situ high-energy X-ray diffraction, computed tomography and electron microscopy tools, we systematically study phase transformations, recrystallization or alloying and diffusion effects to develop customized heat treatment strategies. The talk will provide an overview on the activities in additive manufacturing and heat treatments carried out in recent years.