|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Energy Materials 2017: Materials for Coal-Based Power
||C-3: Atomic-scale Modeling of Point Defects, Phase Stability, and the Formation Mechanism of Z Phases CrMN (M=V, Nb, Ta)
||Daniel F. Urban, Christian Elsaesser
|On-Site Speaker (Planned)
The challenge of raising the steam inlet temperature of fossil-fired power plants calls for creep-resistant steels with a Cr content higher than 9% to achieve sufficient corrosion and oxidation resistance. However, it has been observed that in 11-12% Cr steels strengthened by fine (V,Nb)N particles, precipitation of coarse Z-phase particles, CrMN (M=V,Nb,Ta), in long-term service is unavoidable and detrimental. Hence the task is to control the precipitation of the Z-phase such that fine and long-term stable particles are formed. We present atomistic simulations, using density functional theory, which reveal the mechanisms underlying the formation of Z-phases. The scenario consists of the diffusion of Cr atoms into MN particles and their subsequent clustering in a layered arrangement which finally yields the transformation of (V,Nb)N to Z-phase particles. We study the thermodynamic stability of the Z phase, related structures and predecessors as well as basic phase-formation mechanisms.
||Planned: Stand-alone book in which only your symposium’s papers would appear (indicate title in comments section below)