Abstract
In creep resistant Z-phase strengthened 12% Cr steels, MX (M=Nb, Ta, or V, and X=C and/or N) to Z-phase (CrMN, M=Ta, Nb, or V) transformation plays an important role in achieving a fine distribution of Z-phase precipitates for creep strengthening. Atom probe tomography was employed to investigate the phase transformation in a Nb-based Z-phase strengthened trial steel. Using iso-concentration surfaces with different concentration values, and subtracting the matrix contribution enabled us to reveal the core-shell structure of the transient precipitates between MX and Z-phase. It was shown that Z-phase forms by diffusion of Cr into NbN upon ageing, and Z-phase has a composition corresponding to Cr1+xNb1-xN with x=0.08.
| Original language | English |
|---|---|
| Pages (from-to) | 360-365 |
| Number of pages | 6 |
| Journal | Microscopy and Microanalysis |
| Volume | 23 |
| Issue number | 2 |
| DOIs | |
| State | Published - Apr 1 2017 |
| Externally published | Yes |
Keywords
- 9-12% Cr steels
- Atom probe tomography
- Z-phase
- local magnification
- phase transformation
- precipitates