In-situ alloy synthesis
DFG projekt: In-situ alloy synthesis of ß-NiAl-based alloys using 3D laser powder deposition welding
The continuing development of aerospace propulsion systems is placing increasing demands on the high-temperature structural materials used. As early as 1966, NiAl-based alloys were identified as potential structural materials for high-temperature applications. Their low density, high thermal conductivity, high melting temperature, and good creep and oxidation resistance at high temperatures make them a promising material for structural components in jet engines. Despite the many positive properties of NiAl-based alloys, very low ductility and fracture toughness below the brittle-ductile transition temperature and low high-temperature strength have prevented their industrial use. These problems call for a targeted alloy modification to increase the high temperature strength and room temperature ductility as well as a material specific near net shape processing strategy.
In this project, a wide range of different alloys from the NiAl-Ta-Cr system will be tested for the first time for the additive manufacturing (AM) technique of laser-based directed energy deposition (L-DED). A hybrid process approach consisting of a combination of L-DED and inductive high-temperature preheating will be used to reduce cracking.
Based on thermodynamic calculations of the expected phases, a high-throughput investigation of 13 different alloys with Ta contents up to 14 atomic % and Cr contents up to 34 atomic % is carried out. These alloys are produced combinatorially by in-situ alloying of three different powder materials (NiAl, Ta and Cr) in the form of graded samples and are comprehensively characterized microstructurally and mechanically.