Speaker
Description
Polycrystalline CoNiCr-based alloys show promising properties for future high temperature applications due to their potential to achieve a high y'-volume fraction while retaining a significant processing range. The growing importance on emission reduction through innovative propulsion technologies, such as hydrogen-based aviation fuels or water-enhanced turbofans, requires research into how hydrogen affects the strength and ductility of these alloys.
We conducted a comprehensive investigation into the effects of hydrogen exposure on the polycrystalline CoNiCr-based alloy CoWAlloy3 through a combination of ex-situ X-ray diffraction (XRD) laboratory measurements and neutron diffraction experiments. Our primary objective was to assess the impact of hydrogen on the lattice constants of both the y- and y'-phase. These findings were correlated with tensile tests to evaluate the occurrence of hydrogen-induced embrittlement.
Furthermore, we examined the fracture surfaces of the tested specimens using scanning electron microscopy (SEM) to discern variations in fracture behavior between the reference and hydrogen-exposed samples. Electron backscatter diffraction (EBSD) patterns were acquired at secondary cracks to ascertain whether transgranular or intergranular fracture behavior was present. This multidisciplinary approach allowed us to gain a comprehensive understanding of the hydrogen-related mechanical properties and fracture mechanisms in this alloy.
