Mikrostruktur und mechanische Eigenschaften von elektronenstrahlgeschmolzenen NiAl-(Cr,Mo) und Nb-Si-Cr in-situ Kompositwerkstoffen

Description

Eutectic alloys of the Ni-Al-Cr-Mo and Nb-Si-Cr material systems are excellent for use at high temperatures due to their low density and high melting points. However, due to their insufficient creep resistance and low fracture toughness at room temperature, they have not yet been used as structural materials. This work therefore uses selective electron beam melting as an additive manufacturing process to produce intermetallic in-situ composites with improved mechanical properties. The high cooling rates in selective electron beam melting produce nanostructured phases in NiAl-28Cr-6Mo and Nb-10.9Si-28.4Cr in newly arranged microstructures.
Micro- and macromechanical tests are carried out to characterize the creep properties at elevated temperature and the fracture behaviour at room temperature. The underlying deformation mechanisms are investigated using high-resolution electron microscopy. Important phase transformations in Nb-Si-Cr, as well as interfacial dislocation networks and discontinuous precipitation processes in NiAl-(Cr,Mo) can be observed for the first time with the atom probe.