| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
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Microstructural Template Consisting of a Face-Centered Cubic Matrix with Ordered Precipitates: Microstructural Evolution and Properties
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| Presentation Title |
Correlative High-resolution Characterization of the Early Stages of Precipitation During Direct Aging of Alloy 718 |
| Author(s) |
Felix Theska, Vitor V. Rielli, Keita Nomoto, Flora Godor, Bernd Oberwinkler, Aleksandar Stanojevic, Simon P. Ringer, Sophie Primig |
| On-Site Speaker (Planned) |
Felix Theska |
| Abstract Scope |
Alloy 718 is a polycrystalline, precipitation strengthened Ni-based superalloy used for aircraft engine turbine discs. High-temperature yield strength and creep resistance are achieved by precipitation of nanoscale γ'- (L12 Ni3(Al,Ti)) and γ"- (D022 Ni3(Nb)) particles via coherency and anti-phase boundary strengthening. Compared to conventional ageing, yield strength increments of +10% are achieved via direct ageing by changes in the δ-phase volume fraction, dislocation density, and γ'- and γ"-precipitate duplet and triplet morphology.
However, the detailed γ'- and γ"-precipitate nucleation and growth mechanisms during direct ageing of Alloy 718 remain unknown. Therefore, various high-resolution transmission electron microscopy (HR-TEM) and atom probe microscopy (APM) techniques were used to study the early stages of precipitation for γ'- and γ"-particle volume fraction, radii, density, and morphology. A qualitative microstructural model is introduced to discuss heterogeneous versus homogeneous precipitate nucleation and growth, based on dislocation-precipitate interaction and γ'- and γ"-precipitate morphology evolution. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |