Mechanistic insights into the transformation processes in Z-phase strengthened 12% Cr steels
| Autor: | Hans-Olof Andrén, Saad Ahmed Sheikh, Ardeshir Golpayegani, Sheng Guo, Masoud Rashidi, Fang Liu |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Diffraction Materials science Mechanical Engineering chemistry.chemical_element 02 engineering and technology Atom probe 021001 nanoscience & nanotechnology Microstructure 01 natural sciences law.invention Chromium Precipitation hardening Creep chemistry Chemical engineering Mechanics of Materials law Phase (matter) 0103 physical sciences lcsh:TA401-492 lcsh:Materials of engineering and construction. Mechanics of materials General Materials Science 0210 nano-technology Carbon |
| Zdroj: | Materials & Design, Vol 158, Iss, Pp 237-247 (2018) |
| ISSN: | 0264-1275 |
| Popis: | Compositionally complex Z-phase strengthened 12% Chromium steels are considered as potentially viable materials for components used in highly-demanding environments in steam power plants, operating at a target temperature of 650 °C. To date, however, the transformation processes of various phases into the desired precipitate, i.e., Z-phase CrTaN, are not fully understood. In this research, we first designed and produced three different alloys and then studied the microstructure in the as-tempered and aged conditions (for up to 10,000 h at 650 °C) using advanced electron microscopy, X-ray diffraction, and atom probe tomography. We report on the evolution of the densely distributed MX (Ta(C, N)) and M2X ((Cr, Ta)2N) precipitates into blade-like and bulky Z-phase, respectively. The blade-like precipitates benefit from a smaller size compared to the bulky ones, providing precipitation hardening for creep resistance. We discuss an interactive role of carbon and nitrogen content in the formation of the Z-phase. Our findings pave the way towards designing new alloys with improved properties to serve in harsh environments at 650 °C. Keywords: Creep, Electron microscopy, Atom probe tomography, Precipitates, M2N, MX |
| Databáze: | OpenAIRE |
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