Stress-enhanced growth rate of alumina scale formed on FeCrAlY alloy

Effect of alloyed Lu, Hf and Cr on the oxidation and spallation behavior of NiAl

“…In this study, because of the small addition of Lu/Hf (0.05 at.%) and Cr (2 at.%), the differences of CTE and elastic modulus of the four alloys can be neglected. Assuming there is no stress relaxation due to the rapid cooling after oxidation, the growth stress can be evaluated based on the residual stress at room temperature [31,48,49]: Based on above equations, both the residual stress, ox  and growth stress, growth  in the scale after oxidation are presented in Fig. 8.…”

“…However, the oxidation rate of NiAl-Lu was almost four The effect of impurities, such as REs, on the diffusion rates of ions in Al 2 O 3 is still a subject of discussion [34,50]. It has been reported by Zhao et al [48] that the incorporation of Zr and Y promotes alumina growth. REs, which incorporate into the growing scale during transient oxidation, could segregate to the grain boundaries depending on their sizes and solubility.…”

Microstructure, oxidation behaviour and mechanical properties of Fe2O3 doped yttria-partially-stabilized zirconia coatings produced on metallic substrates by electrophoretic deposition

“…It is found that the development of α-Al 2 O 3 is faster at higher temperatures [49] and in the presence of Fe [50,51] in alumina-forming alloys. As α-Fe 2 O 3 and α-Al 2 O 3 have similar crystalline structure [52][53][54], therefore α-Fe 2 O 3 serves as template to facilitate the nucleation and growth of α-Al 2 O 3 phase at temperature below which phase transition occurs [37,51]. McArdle et al [54] found that the Fe 3+ ions can lower the temperature of α-Al 2 O 3 phase formation from 1200°C to 935°C, because the Fe 3 + ions introduced the preferred nucleation sites, thus reducing the activation barrier for nucleation and favouring the formation of stable α-Al 2 O 3 nuclei [37,55,56].…”

“…As α-Fe 2 O 3 and α-Al 2 O 3 have similar crystalline structure [52][53][54], therefore α-Fe 2 O 3 serves as template to facilitate the nucleation and growth of α-Al 2 O 3 phase at temperature below which phase transition occurs [37,51]. McArdle et al [54] found that the Fe 3+ ions can lower the temperature of α-Al 2 O 3 phase formation from 1200°C to 935°C, because the Fe 3 + ions introduced the preferred nucleation sites, thus reducing the activation barrier for nucleation and favouring the formation of stable α-Al 2 O 3 nuclei [37,55,56]. However, Clarke [57] used time-resolved reflectivity of a laser beam to measure the transformation kinetics of γ-to α-Al 2 O 3 in-situ and revealed that the Fe 3+ ions did increase the phase transformation velocity of Al 2 O 3 .…”

Grain Size Effect and Spinel Transition for Alumina Scale Thermally Grown on Rare Earth–Mg Codoped FeCrAl Alloy

“…[4][5][6] Nevertheless, incorporating trace amounts of reactive elements such as rare earths (RE), titanium, zirconium, and hafnium can significantly reduce the oxidation rate of the alloy or greatly enhance adhesion of oxide films, which is known as the reactive element effect. [7][8][9][10] Although the role of RE in enhancing oxidation resistance properties for an alloy is widely acknowledged, there remains a lack of consensus regarding the action mechanism of RE due to its multiple effects on the alloy-oxide system. It is generally believed that the influence of RE elements on the Al 2 O 3 oxide film is primarily exerted through several mechanisms: 1) RE segregation at grain boundaries (GBs) within the oxides alters the diffusion mechanism from mixed transport of oxygen and aluminum to oxygen-dominated transport; [11][12][13] 2) RE induces changes in microstructures, grain size, and growth direction of oxides; [14][15][16] and 3) desulfurizing by RE reduces S-segregation at the oxide-alloy interface, mitigates interfacial void formation, enhances interfacial strength, and improves adhesion of the oxide film.…”