Coarsening Kinetics of Y2O3 Dispersoid in New Grade of Fe-Al-Cr-Based ODS Alloy

Abstract

Oxide dispersion strengthened (ODS) alloys with a high content of Al are candidate materials for extreme high temperature applications such as turbine blades and other components working at temperatures significantly above 1000 °C. While oxidation kinetics of Fe–Al ODS steels is frequently studied, the stability and growth kinetics of strengthening oxide dispersion is a rarely studied topic. The Fe-10Al-4Cr-4Y2O3 is an experimental material, fabricated at IPM by powder metallurgy route and contains much higher volume fraction of Y2O3 than similar materials. Stability and growth kinetics of Y2O3 particles of our material are studied on 24 samples aged for 0.5, 1, 2, 4, 8, 16, 32 and 72 h at 1200 °C, 1300 °C and 1400 °C. The sizes of at least 600 individual Y2O3 particles are measured on each sample to obtain extensive statistical analysis of the particle growth. The average particle size coarsens from 28.6 ± 0.7 nm to 36.9 ± 0.9 nm in 1200 °C series and to 81.4 ± 5.6 nm in 1400 °C series. The evaluated activation energy of coarsening of Y2O3 particles is 274 ± 65 kJ. The effects of particle coarsening on mechanical properties is demonstrated by HV measurements, which is in very good agreement with the Orowan theory.

The Optimization of Mechanical Alloying Conditions of Powder for the Preparation of a Fe-10Al-4Cr-4Y2O3 ODS Nanocomposite

“…The authors have dealt with the development of the FeAlOY since 2014 [31,[36][37][38][41][42][43]45,46]. The recent efforts include optimization of hot consolidation, secondary recrystallization, and chemical composition with respect to resultant microstructure and high-temperature mechanical properties.…”

“…Thus, the volume fraction cannot be estimated from Figure 9 and its most reliable value can be deduced from the chemical composition of the FeAlOY. coarsening of oxides in the UFG microstructure is significantly accelerated due to fa grain boundary diffusion [38] and it becomes much slower in coarse grains [41]. Furthe more, the oxides shown in Figure 9 are denuded by etching, the time of which significant influences the area density of oxides.…”

“…By comparison, in Figure 9e,f, one can conclude that the time of 170 h is sufficient for a nearly complete dissolution of Y 2 O 3 during MA. It should be noted that the coarsening of oxides in the UFG microstructure is significantly accelerated due to fast grain boundary diffusion [38] and it becomes much slower in coarse grains [41]. Furthermore, the oxides shown in Figure 9 are denuded by etching, the time of which significantly influences the area density of oxides.…”

“…The creep and oxidation-resistant Fe-10Al-4Cr-4Y 2 O 3 (wt.% are used in the whole paper) ODS nanocomposite, denoted as the FeAlOY, has already demonstrated its promising potential for mechanically loaded long-term applications in the temperature range of 1100-1300 • C [31,36,38,41,42]. The FeAlOY is strengthened by 5 vol.% of nanodispersion of pure Y 2 O 3 (the difference between 5 vol.% and 4 wt.% is given by the difference in densities of the matrix 6.5 g/cm 3 and of Y 2 O 3 5.0 g/cm 3 ), being the most resistant phase against coarsening [41,43], and has an appreciable resistance against oxidation up to 1400 • C [44].…”