Preparation and Thermal Stability of a Mechanically Alloyed Oxide Dispersion Strengthened Ferritic Steels

2012 ◽  
Vol 715-716 ◽  
pp. 605-610
Author(s):  
Yu Ren Wen ◽  
Yong Liu ◽  
Dong Hua Liu ◽  
Bei Tang
Keyword(s):  
Thermal Stability ◽  
Nuclear Power ◽  
Oxygen Carrier ◽  
Milled Powder ◽  
Oxide Dispersion Strengthened ◽  
Average Diameter ◽  
Ferritic Steels ◽  
Oxide Dispersion ◽  
Mechanically Alloyed ◽  
The Matrix

Oxide dispersion strengthened ferritic steels (so-called nanostructured ferritic alloys, NFAs), which are candidate structural materials in next generation nuclear power plant, have attracted much attention during recent years. In this work, iron oxide as oxygen carrier and titanium, yttrium hydrides were together mechanically milled with Fe-14Cr-3W gas-atomized powder. The thermal stability and recrystallization behaviour of the as-milled ferritic powder were studied by means of metallography, SEM, TEM and microhardness test. After ball milling for 48h, complete solid solution of bcc-Fe was formed in the as-milled powder. The thermal analysis results show that dispersed oxides with an average diameter of 5nm precipitate from the supersaturated matrix at about 850 °C. During annealing at temperatures from 800 to 1000 °C, a large number of equiaxed grains as fine as few hundreds of microns were found embedding in the matrix; the recrystallized grains stay quite stable and show minor dependence on annealing temperature and time. After being heated to 1200 °C for extended time, abnormal grain growth took place and resulted in bimodal grained structure. The effect of secondary particles on the thermal stability and recrystallization behavior of the ferritic steel was also discussed.

EFTEM and Spectrum Imaging of Mechanically Alloyed Oxide-Dispersion-Strengthened 12YWT and 14YWT Ferritic Steels

2004 ◽  
Vol 10 (S02) ◽  
pp. 662-663 ◽  
Author(s):  
J Bentley ◽  
D T Hoelzer ◽  
D W Coffey ◽  
K A Yarborough
Keyword(s):  
Oxide Dispersion Strengthened ◽  
Ferritic Steels ◽  
Oxide Dispersion ◽  
Mechanically Alloyed ◽  
Spectrum Imaging

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

1977 ◽  
Vol 35 ◽  
pp. 298-299
Author(s):  
Jordi Marti ◽  
Timothy E. Howson ◽  
David Kratz ◽  
John K. Tien
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Stress Rupture ◽  
Oxide Dispersion Strengthened ◽  
Solid Solution Alloy ◽  
Oxide Dispersion ◽  
Creep And Stress Rupture ◽  
Mechanically Alloyed ◽  
Fine Microstructure ◽  
Nickel Base

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.

scholarly journals Microstructure of Oxide Dispersion Strengthened Steel With Cr Content Variation

2020 ◽  
Vol 21 (1) ◽  
pp. 35
Author(s):  
Marzuki Silalahi ◽  
Bernadus Bandriyana ◽  
Arbi Dimyati ◽  
Bambang Sugeng ◽  
Syahfandi Ahda ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase Distribution ◽  
Oxide Dispersion Strengthened ◽  
High Energy ◽  
Oxide Dispersion ◽  
X Ray ◽  
Hardness Tester ◽  
Cr Content ◽  
Ods Steel ◽  
The Matrix

Microstructure and phase distribution of innovative Oxide Dispersion Strengthened (ODS) steel based on Fe-Cr-ZrO2 particularly for application at high temperature reactor with variation of Cr content was analysed. The alloy was synthesized with Cr composition variation of  15, 20 and 25 wt.% Cr, while zirconia dispersoid kept constant at 0.50 wt.%. The samples was synthesized by mechanical alloying comprising of high energy milling for 3 hours followed by vibrated compression with iso-static load at 20 ton. The final consolidation was performed via sintering process for 4 minutes using the Arc Plasma Sintering (APS) technique, a new method developed in BATAN especially for synthesizing high temperature materials. The samples were then characterized by means of scanning electron microscopy (SEM) with energy dispersed X-ray (EDX) analysis capability and X-ray diffraction. The mechanical property of hardness was measured using standard Vickers micro hardness tester to confirmed the microstructure analysis.  The results show that the microstructure of the ODS alloy samples in all variation of Cr content consists generally of cubic Fe-Cr matrix phase with small of porosity and  Zirconia particles distributed homogenously in and around the matrix grains. The achievable hardness was between 142 and 184 HVN dependent consistently on Cr content in which Cr element may cause grain refining that in turn increase the hardness.

scholarly journals Nano-Structured Materials under Irradiation: Oxide Dispersion-Strengthened Steels

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2590
Author(s):  
Joël Ribis ◽  
Isabelle Mouton ◽  
Cédric Baumier ◽  
Aurélie Gentils ◽  
Marie Loyer-Prost ◽  
...  
Keyword(s):  
Nuclear Power ◽  
Ostwald Ripening ◽  
Lattice Structure ◽  
Extreme Environments ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Medium Temperature ◽  
Host Matrix ◽  
Structured Materials ◽  
Nano Oxide

Oxide dispersion-strengthened materials are reinforced by a (Y, Ti, O) nano-oxide dispersion and thus can be considered as nanostructured materials. In this alloy, most of the nanoprecipitates are (Y, Ti, O) nano-oxides exhibiting a Y2Ti2O7 pyrochlore-like structure. However, the lattice structure of the smallest oxides is difficult to determine, but it is likely to be close to the atomic structure of the host matrix. Designed to serve in extreme environments—i.e., a nuclear power plant—the challenge for ODS steels is to preserve the nano-oxide dispersion under irradiation in order to maintain the excellent creep properties of the alloy in the reactor. Under irradiation, the nano-oxides exhibit different behaviour as a function of the temperature. At low temperature, the nano-oxides tend to dissolve owing to the frequent ballistic ejection of the solute atoms. At medium temperature, the thermal diffusion balances the ballistic dissolution, and the nano-oxides display an apparent stability. At high temperature, the nano-oxides start to coarsen, resulting in an increase in their size and a decrease in their number density. If the small nano-oxides coarsen through a radiation-enhanced Ostwald ripening mechanism, some large oxides disappear to the benefit of the small ones through a radiation-induced inverse Ostwald ripening. In conclusion, it is suggested that, under irradiation, the nano-oxide dispersion prevails over dislocations, grain boundaries and free surfaces to remove the point defects created by irradiation.

scholarly journals Effect of Thermo-Mechanical Treatment on the Microstructure and Tensile Properties of the Fe-22Cr-5Al-0.1Y Alloy

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5696
Author(s):  
Hongyan Che ◽  
Yazhong Zhai ◽  
Yingjie Yan ◽  
Yongqing Chen ◽  
Wei Qin ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Mechanical Treatment ◽  
Oxide Dispersion Strengthened ◽  
Fusion Reactors ◽  
Oxide Dispersion ◽  
Grain Sizes ◽  
Powder Metallurgy Process ◽  
The Matrix ◽  
Thermo Mechanical Treatment ◽  
Metallurgy Process

Oxide dispersion strengthened ferritic steel is considered an important structural material in fusion reactors due to its excellent resistance to radiation and oxidation. Fine and dispersed oxides can be introduced into the matrix via the powder metallurgy process. In the present study, large grain sizes and prior particle boundaries (PPBs) formed in the FeCrAlY alloy prepared via powder metallurgy. Thermo-mechanical treatment was conducted on the FeCrAlY alloy. Results showed that microstructure was optimized: the average grain diameter decreased, the PPBs disappeared, and the distribution of oxides dispersed. Both ultimate tensile strength and elongation improved, especially the average elongation increased from 0.5% to 23%.

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