A Preliminary Study of the Development of 9Cr Fe-Base ODS Alloys: The Effects of Minor Elements and Cooling Rate

2007 ◽  
Vol 534-536 ◽  
pp. 617-620
Author(s):  
Jin Sung Jang ◽  
Young Moon Jang ◽  
Yin Zhong Shen
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Complex Oxide ◽  
Minor Elements ◽  
The Matrix ◽  
Hot Isostatic Processing ◽  
Preliminary Study ◽  
Ods Alloys ◽  
The Difference ◽  
Ods Alloy

Three 9Cr Fe-base ODS alloys were prepared by MA (mechanical alloying) and HIP (hot isostatic processing) processes. The addition of Ti was confirmed to have a significant effect on the tensile properties at high temperature as well as at room temperature, while the V addition did not clearly show its effect on the microstructure or on the mechanical porperties at both temperatures. Fine and evenly distributed Y and Ti containing complex oxide was detected in the Ti added ODS alloy. They were attributed to the good high temperature strengths. Different cooling rates from the normalizing temperature did not result in a significant change in the grain boundary characters, but rather significant differences were observed in the mechanical properties. This is mainly attributed to the difference of the matrix phase rather than to the grain size distribution or the grain boundary characters.

Study on Creep Properties of SiCp/AZ61 Composites

2011 ◽  
Vol 189-193 ◽  
pp. 4227-4230
Author(s):  
Hong Yan ◽  
Zhi Min Huang
Keyword(s):  
Thermal Analysis ◽  
High Temperature ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Dynamic Mechanical Thermal Analysis ◽  
Creep Properties ◽  
Casting Technique ◽  
Sic Particles ◽  
The Matrix ◽  
Semi Solid

SiCp/AZ61 composites reinforced with SiC particles were fabricated by semi-solid stirring-melt casting technique. The creep properties of the composites have been studied by dynamic mechanical thermal analysis, micro-structural and XRD observation. The results show that the matrix grains were refined obviously at high temperature with SiC particles introducing and the creep properties of SiCp/AZ61 composites were improved comparing with AZ61 alloy. SiC particles were substituted for Mg17Al12 phase that was easily intenerated at high temperature on grain boundaries. The pinning of SiC particles prevents dislocation and slip of grain boundary at high temperature.

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.

The Effect of Grain-Boundary and Matrix Precipitates on High Temperature Strength in Fe3Al Based Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Ryo Makihara ◽  
Satoru Kobayashi ◽  
Takayuki Takasugi
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Tensile Tests ◽  
High Temperature Strength ◽  
Second Phase ◽  
Proof Stress ◽  
Second Phase Particles ◽  
The Matrix

ABSTRACTThe effect of grain boundary (GB) and matrix precipitates on high temperature strength was investigated in Fe3Al base alloys containing Cr, Mo and C. Tensile tests were conducted at 600°C for three types of microstructures consisting of: (I) film-like κ phase precipitates covering GBs and fine M2C particles in the matrix, (II) only fine M2C particles in the matrix and (III) no second-phase particles in the matrix. It was found that κ films on GBs are more than twice as effective as finely dispersed M2C particles for improving the proof stress.

The Influence of Ni on the Microstructure of Co-Base ODS Alloys

2012 ◽  
Vol 535-537 ◽  
pp. 1011-1014 ◽  
Author(s):  
Lin Zhang ◽  
Xin Bo He ◽  
Ming Li Qin ◽  
Ye Liu ◽  
Xuan Hui Qu
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Mechanical Alloying ◽  
Cleavage Fracture ◽  
Fracture Strength ◽  
Volume Fraction ◽  
Secondary Phases ◽  
The Matrix ◽  
Ods Alloys ◽  
Low Volume

Co-based ODS alloys strengthened by γ΄ precipitates and nanosized oxides are promising high-temperature structural materials. Single solid solution of Al and W in the matrix can not be achieved after mechanical alloying, resulting in the formation of low volume fraction of γ΄ phase and several kinds of secondary phases. The addition of Ni promotes the precipitation of γ΄ phase and reduces the amount of secondary phases by the enlargement of the solid solution limit of Al and W within the matrix. In comparison with the lower fracture strength and cleavage fracture mode of the alloy without the addition of Ni, Ni-containing Co-base ODS alloys exhibit much higher fracture strength and obvious ductile facture mode.

On the Diffusivity of Au in Pb

1985 ◽  
Vol 57 ◽  
Author(s):  
Ann N. Campbell ◽  
David Turnbull
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Ostwald Ripening ◽  
Second Phase ◽  
Precipitate Phase ◽  
Tracer Diffusivity ◽  
Interstitial Defect ◽  
The Matrix ◽  
Kinetics Of ◽  
Good Agreement

AbstractThe precipitation of Pb3Au from dilute Pb(Au) alloys and the subsequent Ostwald ripening of the precipitate phase have been studied. The Au diffusivity which limits the precipitation from Pb(500 at. ppm Au) specimens is in good agreement with Dp = 45 exp[(−20.8 kcal/mol)/RT], found previously to control the precipitation rate in Pb(900–1000 at. ppm Au) alloys (Rossolimo and Turnbull, 1973). In contrast, precipitation from Pb(100 at. ppm Au) alloys and Ostwald ripening in the Pb(500 at. ppm Au) specimens appear to be governed by the high temperature Au tracer diffusivity, DAu = 0.0041 exp[(−9.35 kcal/mol)/RT], which is about 103 times greater than Dp at the temperatures of interest, 75 to 112°C, and is attributed to the motion of a Au interstitial defect. In the 100 ppm alloys the Au is incorporated most easily at the ends of the Pb3Au crystals and a ribbon- or whisker-like morphology results. The particles which form at the grain boundaries in the 500 ppm Au alloy specimens are at least six times larger in volume than the matrix particles and ripen at their expense. The Ostwald ripening kinetics of the grain boundary particles scale with t1/2 rather than with t1/3 as is usual. The Pb3Au formed whiskers, blades, ribbons, or equiaxed particles depending upon the Au concentration and precipitation temperature. The precipitation and ripening kinetics are critically dependent on the morphology of the second phase.

Determination of Corrosion Layers and Protective Coatings on Steels and Alloys Used in Simulated Service Environment of Modern Power Plants

2004 ◽  
Author(s):  
Hubertus Nickel ◽  
Willem J. Quadakkers ◽  
Lorenz Singheiser
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Gas Turbines ◽  
Oxidation Behavior ◽  
Experimental Results ◽  
Growth Mechanisms ◽  
Minor Elements ◽  
Mcraly Coatings ◽  
Ods Alloys ◽  
Cr Steels

The development of modern power generation systems with higher thermal efficiency requires the use of constructional materials of higher strength and improved resistance to the aggressive service atmospheres. In this paper the following examples are discussed: 1) The oxidation behavior of 9% Cr steels in simulated combustion gases: The effects of O2 and H2O content on the oxidation behavior of 9% Cr steels in the temperature range 600–800°C showed that in dry oxygen a protective scale was formed with an oxidation rate controlled by diffusion. In contrast, that in the presence of water vapor, after an incubation period, the scale became non-protective as a result of a change in the oxidation mechanism. 2) The development of NiCrAlY alloys for corrosion resistant coatings and thermal barrier coatings of gas turbine components: The increase of component surface temperature in modern gas turbines leads to an enhanced oxidation attack of the blade coating. Considerable efforts have been made in the improvement of the temperature properties of MCrAlY coatings by the additions of minor elements like yttrium, silicon and titanium. The experimental results show the positive, but different influence of the oxidation behavior of the MCrAlY coatings by the addition of these minor elements. 3) The development of light-weight intermetallics of TiAl-basis: TiAl-based intermetallics are promising materials for future turbine components because of the combination of high temperature strength and low density. These alloys, however, possess poor oxidation resistance at temperatures above 700°C. The experimental results showed that the oxidation behavior of TiAl-based intermetallics can be strongly improved by minor additions of 1–2 at.-% silver. 4) The oxide dispersion strengthened (ODS) alloys provide excellent creep resistance up to much higher temperatures than can be achieved with conventional wrought or cast alloys in combination with suitable high temperature oxidation/corrosion resistance. The growth mechanisms of protective chromia and alumina scales were examined by a two-stage oxidation method with 18O tracer. The distribution of the oxygen isotopes in the oxide scale was determined by SIMS and SNMS. The results show the positive influence of a Y2O3 dispersion on the oxidation resistance of the ODS alloys and its effect on growth mechanisms.

scholarly journals The Structure Effect on Selective Growth in Recrystallization

Texture ◽  
1975 ◽  
Vol 2 (1) ◽  
pp. 35-44 ◽  
Author(s):  
V. Ju. Novikov
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Secondary Recrystallization ◽  
Primary Recrystallization ◽  
Grain Boundary Mobility ◽  
Effective Mobility ◽  
The Matrix ◽  
The Difference ◽  
Grain Misorientation ◽  
Misorientation Angles

The effect of the dependence of grain boundary mobility on misorientation angle and that of structure of the matrix on the growth selectivity during primary and secondary recrystallization are discussed. It was found that the longer is the distance travelled by the growing grain boundaries and the wider the range of the misorientation angles between the new grains and the matrix, the less is the difference between the grain boundary mobilities of the growing grains, necessary for the manifestation of growth selectivity. So during secondary recrystallization the latter is more manifest. In primary recrystallization after moderate deformations, the growth selectivity will be the least obvious when the deformed matrix consists of small differently oriented areas at whose borders new grains nucleate simultaneously. The secondary grain boundaries should be characterized by “effective” mobility, which depends on the number of the adjacent grains and their dimensions, as well as on the growing grain misorientation in relation to these grains. In the small grained material without a texture, the effective boundary mobilities of any grains are equal, and so the growth selectivity in such a material is non-existing.

Effect of TiB2 on Damping Capacity and Dynamic Young's Modulus of 2219 Alloy

2013 ◽  
Vol 470 ◽  
pp. 27-30
Author(s):  
Dong Chen ◽  
Cong Zhou ◽  
Xian Feng Li ◽  
Yi Jie Zhang ◽  
Nai Heng Ma
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Grain Boundary ◽  
Damping Capacity ◽  
Boundary Damping ◽  
Dynamic Young’S Modulus ◽  
The Matrix ◽  
2219 Aluminum Alloy ◽  
Mixed Salts

2219 aluminum alloy reinforced with 10wt. % TiB2 particulate was fabricated through mixed-salts method. The damping capacity and dynamic Yongs modulus was investigated. The damping capacity and dynamic Yongs modulus of 10wt. % TiB2/2219 is higher than that of the matrix alloy.The improved damping capacity is due to dislocation damping at low temperature, and grain boundary damping and interface damping at high temperature.

Relationship between the Valence Electron Structures of Precipitated Phases and Thermostability of Mg-Al-Si Alloy

2011 ◽  
Vol 183-185 ◽  
pp. 2068-2072 ◽  
Author(s):  
Hua Qu ◽  
Wei Dong Liu ◽  
Gang Zhou ◽  
Xiao Lu Shen ◽  
Chuang Liu
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Valence Electron ◽  
Three Dimensional ◽  
Covalent Bond ◽  
Strengthening Mechanism ◽  
Dimensional Structure ◽  
Covalent Bonds ◽  
The Matrix ◽  
Precipitated Phases

The valence electron structures of the matrix and the precipitated phases of Mg17Al12 and Mg2Si of Mg-Al-Si alloy were calculated, then the space structures of covalent bonds of precipitated phases were analysed. The results show that the structures of the two main bonds of Mg17Al12 are connected through the weaker bond G and its thermostability are lower. The strongest bond A of Mg2Si has three dimensional structure and does not exist the weaker segment of covalent bond structure, so its thermostability is high. Under room temperature, the strengthening mechanism of Mg17Al12 and Mg2Si lies in their atom bond force far large than that of the matrix and they effective locate the dislocation movement. When temperature is above 120 °C, the bond G breaks and Mg17Al12 disrupts, so it can not play a role of locating the grain boundary and controlling the grain boundary of high temperature. But it is not easy for the covalent bond structure of Mg2Si to disrupt under high temperature, so it can effectively obstruct the movement of the grain boundary and dislocation.

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