About this Abstract |
Meeting |
MS&T22: Materials Science & Technology
|
Symposium
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Additive Manufacturing of Metals: Microstructure, Properties and Alloy Development
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Presentation Title |
Nitride Formation and Their Influence on Delta Phase Precipitation in Additively Manufactured Nickel Superalloys |
Author(s) |
James Zuback, Selda Nayir, Mingze Gao, Todd A Palmer |
On-Site Speaker (Planned) |
James Zuback |
Abstract Scope |
Elemental segregation is well-known to accelerate the nucleation and growth of delta phase in rapidly solidified nickel superalloys containing niobium. Here, delta phase formation is probed in two additively manufactured Inconel 625 alloys containing high levels of nitrogen and variations in minor alloying elements. Changes in secondary phase formation in as-deposited alloys and after hot isostatic pressing led to strikingly different responses to prolonged exposure at 870 °C. These differences are linked to existing secondary phases, since each type of precipitate contains varying levels of niobium needed for delta phase formation. One alloy with primarily titanium-rich nitrides precipitated delta phase within minutes that grew to a volume fraction of approximately 15 % after 10 hours. In contrast, negligible quantities were detected after 10 hours in the other alloy containing a variety of niobium-rich nitrides. Hot isostatic pressing was found to retard delta precipitation in both alloys up to 100 hours. |