|About this Abstract
|2023 TMS Annual Meeting & Exhibition
|Advanced Characterization of High-temperature Alloys: Phase Evolution during Manufacturing and Service-induced Deformation
|Local Phase Transformation Strengthening in CoNi-base Superalloys
|Andreas Bezold, Nicolas Karpstein, Erdmann Spiecker, Mathias Goken, Steffen Neumeier
|On-Site Speaker (Planned)
Polycrystalline CoNi-base superalloys exhibit a promising property profile consisting of excellent creep strength, good oxidation resistance and a sufficiently large processing window for hot working. In this work, the overall defect structure as well as the atomic structure and chemistry of planar defects in this alloy system are investigated after creep deformation at 750 °C using high resolution scanning transmission electron microscopy. Depending on alloy composition, either γ-like or χ/η-like local phase transformations (LPT) are observed along stacking faults and microtwin boundaries. Similar to their Ni-base counterparts, the occurrence of χ/η-like LPTs is accompanied by a significant increase in creep strength. Atomic-scale energy dispersive X-ray spectroscopy investigations reveal that especially Ta, W and Cr are enriched at these planar defects and trigger the favourable χ/η-like LPTs in complex polycrystalline CoNi-base superalloys. Based on these investigations, potential guidelines for future alloy design are proposed.