Investigation of Ta-MX/Z-Phase and Laves Phase as Precipitation Hardening Particles in a 12 Pct Cr Heat-Resistant Steel
| Autor: | O. Prat, Manuel F. Meléndrez, D. Rojas, Sebastian Suarez, J. P. Sanhueza, José Garcia |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Materials science
Thermo-Calc Modelling 02 engineering and technology Laves phase 01 natural sciences Precipitation hardening 0103 physical sciences Tempering Z-Phase 010302 applied physics Precipitation (chemistry) Metallurgy Metals and Alloys Creep 021001 nanoscience & nanotechnology Condensed Matter Physics TEM characterization Laves Phase Mechanics of Materials Martensite Classical nucleation theory Particle size ddc:620 0210 nano-technology 12%Cr steels |
| Zdroj: | Metallurgical and Materials Transactions A |
| DOI: | 10.22028/d291-27816 |
| Popis: | A 12 pct Cr martensitic/ferritic steel was designed and produced to study Laves and Z-phase as precipitation hardening particles under creep conditions (650 °C). According to thermodynamic calculations, W and Cu additions were selected to ensure the precipitation of Laves after tempering. It is known that Z-phase formation does not follow the classical nucleation theory. Indeed, MX particles are transformed into Z-phase by Cr diffusion from the matrix to the precipitate. Therefore, to promote fast Z-phase formation, Ta, Co, and N additions were used to produce Ta-MX, which will be transformed into Z-phase. The main result achieved was the precipitation of Laves after tempering, with a particle size of 196 nm. As regards to Z-phase, the transformation of Ta-MX into Z-phase after tempering was confirmed by the formation of hybrid nanoparticles of 30 nm. Although W and Ta have a low diffusion in the martensitic/ferritic matrix, characterization of the precipitates after isothermal aging revealed that Laves and Z-phase have fast growth kinetics, reaching 400 and 143 nm, respectively, at 8760 hours. Consequently, creep test at 650 °C showed premature failures after few thousand hours. Therefore, it is expected that future research in the field of martensitic/ferritic steels will focus on the growth and coarsening behavior of Laves and Z-phase. |
| Databáze: | OpenAIRE |
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