About this Abstract |
| Meeting |
MS&T26: Materials Science & Technology
|
| Symposium
|
New Frontiers in Physical Metallurgy of Steels
|
| Presentation Title |
Cu-Enabled NiAl Precipitation in a Mn-Stabilized Austenitic Steel |
| Author(s) |
Keith E. Knipling, Edwin Antillon, Patrick Callahan, David Rowenhorst, Colin Stewart |
| On-Site Speaker (Planned) |
Keith E. Knipling |
| Abstract Scope |
NiAl precipitation strengthening is well established in ferritic and martensitic steels, but its extension to austenitic alloys remains limited by the absence of the BCC crystallographic template that facilitates NiAl nucleation. Here, we investigate precipitation in a Mn-stabilized austenitic steel aged at 580°C using atom probe tomography (APT), transmission electron microscopy (TEM), density functional theory (DFT), classical nucleation theory (CNT), and thermodynamic and kinetic modeling.Three nanoscale phases form during ageing: FCC Cu, B2 NiAl, and Cr-rich carbides. APT reveals that NiAl nucleates via a metastable ordered FCC (L1<sub>2</sub>) precursor enabled by Cu. CNT parameterized with DFT-derived driving forces confirms that this L1<sub>2</sub> metastable precursor provides the only viable low-barrier nucleation pathway to B2 NiAl in austenite. These results identify Cu as the enabling element for NiAl precipitation strengthening directly in austenite, opening new alloy design strategies for fully austenitic high-performance steels. |