Conversion of MX nitrides to Z-phase in a martensitic 12% Cr steel

Kinetics of Z-Phase Precipitation in 9 to 12 pct Cr Steels

“…1-Two typical transformation processes of small MX (a) and large MX (b) precipitates into Z-phase by in-diffusion of Cr in the 12CrVNbN alloy after exposure at 1000 h/923K (650°C). [8] Scale in metallic at. pct.…”

“…crystallographically into Z-phase. [5,8,9] This results in Z-phase having two different crystal structures, which can coexist in a single precipitate particle. [10] The primary Z-phase crystal structure is tetragonal with lattice parameters of a = 0.286 nm and c = 0.739 nm, and it is likely the most thermodynamically stable.…”

Thermomechanical controlled processing to achieve very fine grains in the ISO 5832-9 austenitic stainless steel biomaterial

“…When the particles are small, they tend to decrease the mobility of grain boundaries formed upon straining by dynamic recrystallization and during the interpass time by static and metadynamic recrystallization. In turn, when precipitates coalesce, a degradation of fatigue properties and corrosion resistance of the material is noticed [11][12][13][14][15][16]. The formation of Z-phase is unclear at present and not well established whether it is formed from prior nitride precipitates as proposed by some authors [13,[17][18][19] or directly nucleated as suggested by others [8,20,21].…”

Prospects for Martensitic 12 % Cr Steels for Advanced Steam Power Plants

“…Instead, the Z-phase forms only by diffusion of Cr into pre-existing MN nitrides. Coarse Z-phases form by fast growth of fully transformed particles, including the consumption of other fine MN, which dissolve [25][26][27]. This understanding led to the idea that a strong acceleration of the Z-phase transformation could provide a fine distribution of Zphase particles with high particle strengthening.…”