The effect of Zr on precipitation in oxide dispersion strengthened FeCrAl alloys

STEP Report on Advanced ODS FeCrAl Alloys for Fission Applications

“…Additionally, atom maps for molecular ion species (Y, YO, AlO, and Zr) are also shown to highlight which elemental species are within the precipitates (Y, Al, O) and which are not (i.e., Zr). This behavior is consistent with a recently published work that highlights the importance of C and N on the precipitation state in these CrAZY alloys [21], which is the main reason why the precipitation state in this alloy differs from that previously reported for similar FeCrAlZrY alloys developed elsewhere [22]. The additional 1,200°C anneal required to recrystallize the Z7 microstructure coarsened the average precipitate diameter because the diameters for Z6 and Z7 were calculated to be 5.3 and 7.5 nm, respectively.…”

“…Although processing effects pertaining to recent developments in FY20 are discussed later in this work, it is worth noting that the work performed at ORNL coupled with parallel development efforts on different ~15Cr ODS FeCrAl alloys in Japan [22,32,33] caused significant leaps in ODS FeCrAl tube processing to accomplished. Additionally, it was demonstrated that nanoprecipitate size and mechanical properties can be optimized, depending on the ball milling and thermomechanical processing temperatures used for alloy production [10,14,21]. Gaps pertaining to cladding behavior in reactor environments are readily apparent in Table 3.…”

Research Progress of ODS FeCrAl Alloys–A Review of Composition Design

“…In addition, coarser precipitates enriched in Zr elements are highlighted in purple, but no Y–Zr–O phases are found in the matrix. Massey et al [ 151 ] carried out a thermodynamic assessment of Zr precipitation and found that (C,N) solute impurities significantly affect the equilibrium phases within the alloy system. As shown in Figure 23 a, when C and N exist in the matrix, the primary phases that are expected to form are Zr(C,N), AlN, Cr carbides, and complex (Y, Al, and O)-rich oxides, such as YAP and YAG.…”

“…Shi et al [ 153 ] found coarse complex Al 2 O 3 /Y 4 Zr 3 O 12 oxides, which were defined as “appendage oxides”, distributing in the matrix of an as-deposited sample prepared by laser-engineered net-shaped (LENS) technology. A co-precipitation consisting of ZrC and Al 2 O 3 with Y segregation to the surface of the alumina precipitate was discovered in ZY10C60 annealed powder [ 151 ]. Nanoscale Y 4 Zr 3 O 12 /YAP/Al 2 O 3 appendage oxides [ 143 ] were recently found in the Fe–12Cr–5Al–2W–1Zr model alloy prepared by SPS.…”

High-Temperature Oxidation Properties and Microstructural Evolution of Nanostructure Fe-Cr-Al ODS Alloys

“…To conquer this issue, Zr element is used to form finer Y-Zr-O particles due to the higher binding energies of Y-Zr-O than those of Y-Al-O. Thus, the combined addition of Y 2 O 3 and Zr elements can significantly improve the high-temperature strength of the Fe-Cr-Al alloy [ 12 , 13 , 14 ].…”