Excessive ThO2 Particle Growth in Ni-2ThO2 at High Temperature

1970 ◽  
Vol 28 ◽  
pp. 416-417
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
Particle Size ◽  
Metal Matrix ◽  
Oxide Dispersion Strengthened ◽  
Particle Growth ◽  
Interparticle Spacing ◽  
Refractory Oxide ◽  
Oxide Dispersion ◽  
Volume Percent ◽  
Oxide Particles ◽  
Cold Worked

It is generally accepted that a uniform spatial distribution of fine refractory oxide particles is required in an oxide-dispersion-strengthened metal to provide good elevated-temperature strengths. The presence of these particles stabilizes the cold-worked microstructure by anchoring low-angle cell boundaries and by restricting the motion of dislocations during loading. Such action by the particles must be a function of the interparticle spacing as is proposed by the Orowan model for yield stress. For a given volume percent of oxide in the metal matrix, the interparticle spacing is directly proportional to the particle size. Therefore, particle growth during the processing of oxide-dispersion-strengthened metals increases the interparticle spacing and inherently decreases the strength.

Thoria Particle Growth in Ni-2%ThO2 by a Sintering Mechanism

1971 ◽  
Vol 29 ◽  
pp. 210-211
Author(s):  
E. R. Kimmel ◽  
W. Scheithauer
Keyword(s):  
Spatial Distribution ◽  
Fine Particles ◽  
Oxide Dispersion Strengthened ◽  
Particle Growth ◽  
Mechanical Processing ◽  
High Temperature Mechanical Properties ◽  
Annealing Conditions ◽  
Oxide Particles ◽  
Cold Worked ◽  
And Control

Good high-temperature mechanical properties exhibited by oxide-dispersion-strengthened metals are strongly dependent on the presence of a cold worked microstructure which is thermally stabilized by fine oxide particles uniformly distributed in the metal matrix. Microstructural features of this nature are produced by subjecting the material to thermal mechanical processing. Such processing has a two-fold purpose—to improve the spatial distribution and to control the size of the dispersion.The typical state of the dispersion in the hot consolidated P-M plate can best be described as one of fine particles which tend to be highly agglomerated, i.e. a poor spatial distribution. By properly controlling deformation and annealing conditions during thermal mechanical processing of plate to sheet, one can greatly improve the spatial distribution and control the size of the oxide particles. If agglomerates consist of fine particles only in close physical arrangement, deformation will disperse them and thus improve the total spatial distribution.

scholarly journals ODS EUROFER Steel Strengthened by Y-(Ce, Hf, La, Sc, and Zr) Complex Oxides

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1148 ◽  
Author(s):  
Roman Husák ◽  
Hynek Hadraba ◽  
Zdeněk Chlup ◽  
Milan Heczko ◽  
Tomáš Kruml ◽  
...  
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Complex Oxides ◽  
Oxide Dispersion Strengthened ◽  
Interparticle Spacing ◽  
Oxide Dispersion ◽  
Strengthening Effect ◽  
Dispersion Strengthening ◽  
Doping Element ◽  
Average Grain Size

Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.

scholarly journals Growth of oxide particles in FeCrAl- oxide dispersion strengthened steels at high temperature

2017 ◽  
Vol 493 ◽  
pp. 180-188 ◽  
Author(s):  
N.H. Oono ◽  
S. Ukai ◽  
S. Hayashi ◽  
S. Ohtsuka ◽  
T. Kaito ◽  
...  
Keyword(s):  
High Temperature ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Oxide Particles

Y2O3 Morphology in an Oxide Dispersion Strengthened FeAl Alloy Prepared by Mechanical Alloying

1996 ◽  
Vol 460 ◽  
Author(s):  
B. J. Inkson ◽  
P. L. Threadgill
Keyword(s):  
Mechanical Alloying ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Feal Alloy ◽  
Oxide Particles

ABSTRACTThe microstructure of an oxide dispersion strengthened FeAl (Zr,B) alloy, manufactured by mechanical alloying then extrusion, has been examined by HREM. Y2O3 is dispersed throughout the FeAl matrix as particles, ranging in size from 5nm upwards, which are effective in pinning the bulk dislocations. Although in the main the observed oxide particles are irregular in morphology, a significant minority of particles exhibit faceted surfaces. In particular, the facets of the Y2O3 particles are observed to coincide with {100}B2, {110}B2 and {112}B2 planes of the surrounding bulk FeAl matrix. In addition, HREM imaging reveals uncoupled 1/2<111>FeAl superpartial dislocations lying a few nanometres from some of the FeAl - Y2O3 interfaces.

TEM and HRTEM study of oxide particles in an Al-alloyed high-Cr oxide dispersion strengthened steel with Zr addition

2014 ◽  
Vol 444 (1-3) ◽  
pp. 441-453 ◽  
Author(s):  
Peng Dou ◽  
Akihiko Kimura ◽  
Ryuta Kasada ◽  
Takanari Okuda ◽  
Masaki Inoue ◽  
...  
Keyword(s):  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Oxide Dispersion Strengthened Steel ◽  
Zr Addition ◽  
Oxide Particles

Oxidation of Oxide Dispersion Strengthened Steels: II. Kinetics and Mechanism

2013 ◽  
Vol 748 ◽  
pp. 106-111
Author(s):  
Jae Hoon Lee
Keyword(s):  
Grain Refinement ◽  
Oxidation Resistance ◽  
Oxide Dispersion Strengthened ◽  
Oxide Dispersion ◽  
Protective Oxide ◽  
Alumina Layer ◽  
Ods Steel ◽  
Time Period ◽  
Oxide Particles ◽  
Ods Steels

The oxidation resistance of 18%Cr-oxide dispersion strengthened (ODS) ferritic steels with and without 5%Al has been investigated in air at 700900 °C for time period up to 540 h. The oxidation rate of ODS steels is significantly dependent on the oxidation time and temperature. Compared to Al-containing ODS steel, the finer grains of Al-free ODS steel are due to the formation of smaller coherent oxide particles which suppress the steel's grain growth. The grain refinement of ODS steels is expected to allow rapid segregation of Cr or Al to the steel surface, so that the continuous Fe-Cr spinel or alumina layer is formed quickly in comparison to the alloys without oxide particles dispersion. Therefore, the excellent oxidation resistance of ODS steels is owing to the formation of continuous, protective oxide layers which correlate with oxide nanoparticles and grain refinement.

Sign in / Sign up

Export Citation Format

Share Document