scholarly journals Fundamental Improvement of Creep Resistance of New-Generation Nano-Oxide Strengthened Alloys via Hot Rotary Swaging Consolidation

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5217
Author(s):  
Jiří Svoboda ◽  
Lenka Kunčická ◽  
Natália Luptáková ◽  
Adam Weiser ◽  
Petr Dymáček
Keyword(s):  
Volume Fraction ◽  
Secondary Recrystallization ◽  
Grain Morphology ◽  
Oxide Dispersion Strengthened ◽  
High Volume ◽  
Coarse Grained ◽  
Mechanically Alloyed ◽  
Rotary Swaging ◽  
New Generation ◽  
Ods Alloy

New-generation oxide dispersion-strengthened (ODS) alloys with a high volume fraction of nano-oxides of 5% are intended to become the leading creep- and oxidation-resistant alloys for applications at 1100–1300 °C. Hot consolidation of mechanically alloyed powders by intensive plastic deformation followed by heat treatment of the alloys are the key aspects for achieving top creep properties, typically ensured by a coarse-grained microstructure strengthened with homogeneously dispersed, very stable yttrium nano-oxides. The rotary swaging method proves to be favourable for hot consolidation of the new-generation ODS alloy presented. Compared to specimens consolidated by hot rolling, consolidation by hot rotary swaging predetermines the formation of coarse grains with a very high aspect ratio during subsequent secondary recrystallization. Such a grain morphology increases the creep strength of the new-generation ODS alloy considerably.

scholarly journals Influence of Hot Consolidation Conditions and Cr-Alloying on Microstructure and Creep in New-Generation ODS Alloy at 1100 °C

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5070 ◽  
Author(s):  
Jiří Svoboda ◽  
Natália Luptáková ◽  
Milan Jarý ◽  
Petr Dymáček
Keyword(s):  
Hot Rolling ◽  
Secondary Recrystallization ◽  
Oxide Dispersion Strengthened ◽  
Coarse Grained ◽  
Mechanically Alloyed ◽  
Creep Properties ◽  
Ods Alloys ◽  
Rolling Temperatures ◽  
New Generation ◽  
Ods Alloy

The coarse-grained new-generation Fe-Al-Y2O3-based oxide dispersion strengthened (ODS) alloys contain 5 vol.% homogeneously dispersed yttria nano-precipitates and exhibit very promising creep and oxidation resistance above 1000 °C. The alloy is prepared by the consolidation of mechanically alloyed powders via hot rolling followed by secondary recrystallization. The paper presents a systematic study of influence of rolling temperature on final microstructure and creep at 1100 °C for two grades (Fe-10Al-4Y2O3 and Fe-9Al-14Cr-4Y2O3 in wt%) of new-generation ODS alloys. The hot rolling temperatures exhibit a rather wide processing window and the influence of Cr-alloying on creep properties is evaluated as only slightly positive.

scholarly journals High Temperature Cyclic Plastic Response of New-Generation ODS Alloy

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 804
Author(s):  
Alice Chlupová ◽  
Ivo Šulák ◽  
Jiří Svoboda
Keyword(s):  
High Temperature ◽  
Oxide Dispersion Strengthened ◽  
Step Test ◽  
Coarse Grained ◽  
Fatigue Properties ◽  
Oxide Dispersion ◽  
Ods Alloys ◽  
New Generation ◽  
Near Future ◽  
Ods Alloy

The very recently developed coarse-grained new-generation oxide dispersion strengthened (ODS) alloys containing 5 vol.% homogeneously distributed yttrium nano-precipitates seems to be a promising oxidation-resistant structural material for applications at temperatures above 1000 °C. The primary aim of the present paper is the introduction of the new-generation oxide dispersion strengthened (ODS) alloy and the first testing of its high temperature fatigue properties at 800 °C, concurrently demonstrating a novel and very efficient methodology by using an incremental fatigue step test. The successful application of the methodology motivates the authors to test the fatigue properties of new generation ODS alloys at 1000–1200 °C in the near future.

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 The Influence of Aluminum Content on Oxidation Resistance of New-Generation ODS Alloy at 1200 °C

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1478 ◽  
Author(s):  
Luděk Stratil ◽  
Vít Horník ◽  
Petr Dymáček ◽  
Pavla Roupcová ◽  
Jiří Svoboda
Keyword(s):  
Oxidation Resistance ◽  
Cross Sections ◽  
Aluminum Content ◽  
Energy Dispersive Spectrometer ◽  
Oxide Dispersion Strengthened ◽  
Xrd Analysis ◽  
Al Content ◽  
Α Al2o3 ◽  
New Generation ◽  
Ods Alloy

The aim of the paper is to evaluate the effect of aluminum content on the oxidation resistance of new-generation of oxide dispersion strengthened (ODS) alloy at 1200 °C. Three grades of the alloy of chemical composition Fe-15Cr-xAl-4Y2O3 with different Al contents x = 0.3 wt.%, 2.0 wt.% and 5.5 wt.% are prepared by mechanical alloying. The alloys are consolidated by high temperature rolling followed by heat treatment. To study the oxidation resistance the samples are isothermally aged in the air for 1 h, 4 h, 16 h and 64 h at 1200 °C. The oxidation kinetics, composition and formation mechanism of the oxide layers are analyzed. The weight gain of prepared steels is estimated. The kinetics of oxidation is studied on metallographic cross-sections of the exposed samples by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis. The oxides on the surfaces are identified by X‑ray diffraction (XRD) analysis. The Al content significantly enhances the oxidation resistance of the alloy. For a sufficiently high Al content in the alloy a compact oxide layer of α‑Al2O3 on the surface is formed, which significantly suppresses further oxidation process.

Recrystallization of Nickel and Ni Alloy Substrates for YBCO Coated Conductors

2000 ◽  
Vol 659 ◽  
Author(s):  
Rainer Nast ◽  
Bernhard Obst ◽  
Wilfried Goldacker ◽  
Wolfgang Schauer
Keyword(s):  
Grain Growth ◽  
Volume Fraction ◽  
Secondary Recrystallization ◽  
Cube Texture ◽  
High Volume ◽  
Coated Conductors ◽  
Recrystallization Temperature ◽  
Cube Orientation ◽  
Ni Alloy ◽  
Kinetics Of

ABSTRACTTo avoid grain boundary grooving and abnormal grain growth during recrystallization of nickel and Ni alloy substrate tapes, the commonly used high recrystallization temperatures must be lowered.The development of the cube orientation is a nucleation-growth process. So the kinetics of the cube recristallization is strongly temperature dependent, and there is a very marked effect of the stacking fault energy (SFE) of the specific alloy on the activation energy. Concurrently with measurements of the formation kinetics of the cube orientation, the recrystallization texture of Ni (+99,99 wt.%), NiCr10 wt.% and NiMn10 wt.% tapes in dependence on the deformation history, the annealing temperature and time was investigated. Profile rolling to a rectangular rod, without further high temperature annealing, leads to a worse cube texture compared to round swaged rods with an in-plane 200 peak splitting. The increase of the recrystallization temperature and time sharpens the texture due to grain growth, limited by the occurrence of secondary recrystallization when a sample specific temperature is exceeded.In binary Ni alloys the commonly used alloying elements reduce the SFE. This favors the formation of recrystallization twins {122}<212> obstructing the oriented coating. In Mn alloyed tapes this effect is strongly pronounced. The tapes show a good cube texture, but also a high volume fraction of twins due to the low SFE. To suppress the twin formation we investigated ternary Ni based alloys with respect to possibly increased SFE and report first results.

Influence of Plastic Deformation on Recrystallized Microstructure of Fe-Base ODS Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 2209-2214
Author(s):  
Carlos Capdevila ◽  
I. Toda ◽  
J. Chao ◽  
Carlos García de Andrés
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Mechanical Alloying ◽  
Recent Work ◽  
Oxide Dispersion Strengthened ◽  
Coarse Grained ◽  
Oxide Dispersion ◽  
Large Influence ◽  
Ods Alloy ◽  
Number Of Authors

The ferritic oxide dispersion strengthened alloys (ODS) are manufactured using the mechanical alloying process. The development of a coarse grained microstructure during the recrystallization has been noted and discussed by a number of authors but, the mechanism of grain control remains uncertain. Recent work has emphasized the large influence of non-uniformities on the development of the recrystallized microstructure. The purpose of the present work was to study the effect of non-uniform plastic strain on recrystallization of Fe-base ODS alloy named MA 957.

scholarly journals Effect of Extensive and Limited Plastic Deformation on Recrystallized Microstructure of Oxide Dispersion Strengthened Fe-Cr-Al Alloy

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1052
Author(s):  
Carlos Capdevila ◽  
Rosalia Rementeria ◽  
Maria Aranda ◽  
Javier Vivas ◽  
Jesus Chao ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Mechanical Alloying ◽  
Recent Work ◽  
Grain Growth ◽  
Oxide Dispersion Strengthened ◽  
Coarse Grained ◽  
Al Alloy ◽  
Oxide Dispersion ◽  
Plastic Strains ◽  
Ods Alloy

Ferritic oxide dispersion-strengthened alloys (ODS) are manufactured using a mechanical alloying process. The development of a coarse-grained microstructure during recrystallization has been detected and discussed by several authors, but the mechanism of grain growth remains uncertain. Recent work has emphasized the large influence of non-uniformities on the development of the recrystallized microstructure. The purpose of the present work is to study the effect of both slight heterogeneous plastic strains and strong directional deformation on recrystallization of a ferritic Fe-base ODS alloy.

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