Superior Radiation Resistance of ODS Ferritic Steels

2010 ◽  
Vol 654-656 ◽  
pp. 2791-2794 ◽  
Author(s):  
Ryuta Kasada ◽  
Hiromasa Takahashi ◽  
Hirotatsu Kishimoto ◽  
Kentaro Yutani ◽  
Akihiko Kimura
Keyword(s):  
Ferritic Steel ◽  
Ion Irradiation ◽  
Oxide Dispersion Strengthened ◽  
Preferential Formation ◽  
Nano Oxide ◽  
Dual Beam ◽  
Transmission Electron ◽  
The Matrix ◽  
Oxide Particles ◽  
Helium Implantation

The oxide dispersion strengthened (ODS) ferritic steel and non-ODS reduced-activation ferritic (RAF) steel were irradiated at 773 K by means of a dual-beam ion irradiation technique to a dose of 0.4 dpa with simultaneous helium implantation up to 1000 appm. Microstructural changes were investigated by transmission electron microscopy. The RAF steel showed a preferential formation of cavities at grain boundaries, precipitate interfaces and dislocations. In contrast, the ODS ferritic steel showed a homogeneous and fine distribution of cavities in the matrix. This paper discusses the superior resistance of the ODS ferritic steel against development of cavities in terms of the effects of nano-oxide particles dispersed in the matrix.

Characterization of oxide particles in ODS austenitic stainless steel after heavy ion irradiation up to high doses

2011 ◽  
Vol 1298 ◽  
Author(s):  
Hiroshi Oka ◽  
Yosuke Yamazaki ◽  
Hiroshi Kinoshita ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Ion Irradiation ◽  
Hot Extrusion ◽  
Oxide Dispersion Strengthened ◽  
Complex Oxide ◽  
Heavy Ion ◽  
Oxide Particles ◽  
The Difference ◽  
High Doses

ABSTRACTOxide dispersion strengthened austenitic stainless steel (ODS316), which is based on advanced SUS316 steel, has been developed by mechanically alloying and hot extrusion. Hafnium and titanium were added to make a fine distribution of oxide particles. The stability of oxide particles dispersed in ODS316 under irradiation was evaluated after 250 keV Fe+ irradiation up to high doses at 500 °C. TEM observation and EDS analysis indicated that fine complex oxide particles with Y, Hf and Ti were mainly dispersed in the matrix. There are no significant changes in the distribution and the size of oxide particles after irradiation. It was also revealed that the constitution ratio of Ti in complex oxide appeared to be decreased after irradiation. This diffuse-out of Ti during irradiation could be explained by the difference in oxide formation energy among alloying elements.

Helium Implantation of Ultrafine Grained Tungsten within a TEM

2014 ◽  
Vol 1645 ◽  
Author(s):  
K. Hattar ◽  
O. El-Atwani ◽  
M. Efe ◽  
T.J. Novakowski ◽  
A. Suslova ◽  
...  
Keyword(s):  
Nuclear Reactors ◽  
Ion Irradiation ◽  
Tungsten Alloys ◽  
Helium Bubbles ◽  
Transmission Electron ◽  
Radiation Properties ◽  
Ultrafine Grained ◽  
Theoretical Predictions ◽  
Helium Implantation ◽  
Future Work

ABSTRACTMany theoretical predictions have suggested that the confined length scales and increased interface density of various nanostructured materials may result in desired thermal, mechanical, and radiation properties. An important aspect of this for next generation nuclear reactors is understanding the change in swelling resulting from helium evolution in tungsten alloys, as a function of grain size and grain boundary type. This study investigated this using a new ion irradiation transmission electron microscope (TEM) facility that has been developed at Sandia National Laboratories and is capable of ion implanting helium at energies up to 20 keV. It was demonstrated in this feasibility study that helium could be implanted into an ultrafine grained tungsten TEM sample produced by severe plastic deformation. The size and density of the helium bubbles formed during the experiment appear nearly constant; while the larger voids formed appear to be dependent on the local microstructure. Future work is underway to both optimize the facility, as well as better understand the evolution of ultrafine grained tungsten resulting from both helium implantation and displacement damage.

High-Temperature In Situ Straining Experiments in the High-Voltage Electron Microscope

1998 ◽  
Vol 4 (3) ◽  
pp. 226-234 ◽  
Author(s):  
Ulrich Messerschmidt ◽  
Dietmar Baither ◽  
Martin Bartsch ◽  
Bernd Baufeld ◽  
Bert Geyer ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Oxide Dispersion Strengthened ◽  
Voltage Electron ◽  
Dislocation Plasticity ◽  
Transmission Electron ◽  
Macroscopic Deformation ◽  
Oxide Particles ◽  
Short Time

Design rules are described here for high-temperature straining stages for transmission electron microscopy. Temperatures above 1000°C can be attained by electron bombardment of the specimen grips. Thermal equilibrium can be reached in a short time by carrying off the heat by water cooling. Some applications of this stage are described. Ferroelastic deformation was observed at 1150°C in t′ and partially stabilized zirconia, which changes the microstructure for successive dislocation plasticity. In the oxide-dispersion-strengthened alloy INCOLOY MA 956, dislocations are impeded by oxide particles and move smoothly between the particles. At high temperatures, both the resting and traveling times control the average dislocation velocity. In MoSi2 single crystals of a soft orientation, dislocations with 1/2〈111〉 Burgers vectors are created in localized sources and move on {110} planes in a viscous manner. The dislocations in Al-Pd-Mn single quasicrystals are oriented in preferred crystallographic directions and move in a viscous way as well. On the basis of in situ observations, conclusions are drawn for interpreting macroscopic deformation behavior at high temperatures.

Effects of Consolidation Process on the Microstructure and Mechanical Properties of ODS Ferritic Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 507-512 ◽  
Author(s):  
Tong Liu ◽  
Hai Long Shen ◽  
Tong Wen Zhang ◽  
Mu Zhu ◽  
Cheng Gong Qin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Hot Isostatic Pressing ◽  
Oxide Dispersion Strengthened ◽  
Consolidation Process ◽  
Ferritic Alloy ◽  
Plasma Sintering ◽  
The Matrix ◽  
Spark Plasma ◽  
Oxide Particles

The oxide-dispersion-strengthened (ODS) ferritic alloy powders (Fe-14Cr-3Al-2W-0.1Ti-0.35Y2O3) were prepared by mechanical alloying (MA) at a rotation speed of 720 rpm for 24 h. All the elements were mixed homogenously in the powder, and Cr and Al dissolved in α-Fe after MA. The bulk samples were produced by spark plasma sintering (SPS) at 950 and 50 MPa and by hot isostatic pressing (HIP) at 1150 and 130 MPa, respectively. The SPS sample showed a tensile strength of 730 MPa and a poor ductility due to the existence of pores in microsize. The HIP sample had a high tensile strength of 980 MPa, yield strength of 710 MPa and elongation of 10.3 %. The excellent mechanical properties of the HIP sample was due to the small grain size of the matrix of about 400 nm and the fine oxide particles of 5-40 nm.

Creep deformation behavior of nano oxide dispersion strengthened Fe–18Cr ferritic steel

Materialia ◽  
2020 ◽  
Vol 12 ◽  
pp. 100788 ◽  
Author(s):  
Rajesh Jarugula ◽  
P. Suresh Babu ◽  
S. Ganesh Sundara Raman ◽  
G. Sundararajan
Keyword(s):  
Creep Deformation ◽  
Deformation Behavior ◽  
Ferritic Steel ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Nano Oxide

The Influence of Helium and ODS on the Irradiation-Induced Hardening of Eurofer97 at 300°C

2010 ◽  
Vol 73 ◽  
pp. 124-129 ◽  
Author(s):  
Cornelia Heintze ◽  
Frank Bergner ◽  
Reinhard Kögler ◽  
Rainer Lindau
Keyword(s):  
Mechanical Properties ◽  
Ion Irradiation ◽  
Single Beam ◽  
Damage Layer ◽  
Dual Beam ◽  
Hardness Increase ◽  
Oxide Particles ◽  
Underlying Mechanisms ◽  
Fe Ions ◽  
Post Implantation

The influence of helium on the mechanical properties of reduced-activation ferritic/martensitic Cr-steels under fusion-relevant irradiation conditions is still a concern. While the fact that He can influence the mechanical properties is well established [1,2], the underlying mechanisms are not fully understood [1,2]. In this work the effect of He and displacements per atom (dpa) on the irradiation-induced hardening of Eurofer97 at 300°C was studied. Self-ion irradiation was applied to simulate the neutron-irradiation-induced damage. Helium was implanted prior to (pre-implantation), simultaneously (dual-beam irradiation) or following the (post-implantation) self-ion irradiation to investigate the He effect. Nanoindentation was used in order to characterize the damage layer. Under the present conditions (300°C, 1 dpa, 10 appmHe) the observed hardening increased in the following order: single-beam Fe-ion irradiation/pre-implantation < simultaneous implantation < post-implantation. We conclude, that there is a significant interaction between damage and He. Additionally, Eurofer97 and ODS-Eurofer were irradiated with Fe ions up to 1 and 10 dpa to study the effect of the oxide particles on the irradiation-induced hardening. We have found a higher irradiation-induced hardening at 1 dpa for ODS-Eurofer but a steeper hardness increase per dpa up to 10 dpa for Eurofer97.

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