Investigation of the Strengthening Mechanisms of Dispersion-strengthened Alloys PDF Download
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Author: Richard J. Murphy
Publisher:
ISBN:
Category : Dispersion strengthening
Languages : en
Pages : 38
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Book Description
In an effort to produce dispersion-strengthened alloys with more versatile strength properties than those reported for oxide dispersion strengthened systems, the systems Ni-TiC and Ni-TiB2 were studied. Diffusion couples of dilute alloys of Ni-C and Ni-Ti as well as of Ni-B and Ni-Ti were studied to determine the conditions necessary for the formation of a fine dispersion of TiC and TiB2 in nickel. TiB2 was found to be unsuitable for this type of application. Nickel-base alloys with a dispersion of TiC were prepared by several powder metallurgical techniques as well as by internal carburization of Ni-Ti chips. The mechanical properties of these alloys were studied at room temperature and 815C and a comparison made with the properties of conventional alloys reported for these temperatures. Transmission electron microscopy was used to study the elastic strain fields associated with dispersoid particles in the Ni-Al2O3 and Cu-Al2O3 systems, prepared by internal oxidation. (Author).
Author: Richard J. Murphy
Publisher:
ISBN:
Category : Dispersion strengthening
Languages : en
Pages : 38
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Book Description
In an effort to produce dispersion-strengthened alloys with more versatile strength properties than those reported for oxide dispersion strengthened systems, the systems Ni-TiC and Ni-TiB2 were studied. Diffusion couples of dilute alloys of Ni-C and Ni-Ti as well as of Ni-B and Ni-Ti were studied to determine the conditions necessary for the formation of a fine dispersion of TiC and TiB2 in nickel. TiB2 was found to be unsuitable for this type of application. Nickel-base alloys with a dispersion of TiC were prepared by several powder metallurgical techniques as well as by internal carburization of Ni-Ti chips. The mechanical properties of these alloys were studied at room temperature and 815C and a comparison made with the properties of conventional alloys reported for these temperatures. Transmission electron microscopy was used to study the elastic strain fields associated with dispersoid particles in the Ni-Al2O3 and Cu-Al2O3 systems, prepared by internal oxidation. (Author).
Author: Nicholas John Grant
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 44
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Dispersion-strengthening mechanisms are under investigation in alloys based on the Nb-- V system for the purpose of improving stress-rupture properties. Ten compositions containing small C additions in combination with Hf or Zr were prepared by nonconsumable-electrode arc melting. Powder metallurgy preparation of alloys containing dispersed refractory particles is also under investigation. Minus 325 mesh powders of a V--Nb--Ti alloy were produced by the hydride process; the sintered compacts were over 90% of theoretical density and possessed a relatively high degree of compressive ductility at room temperature. (auth).
Author: Facundo Rolf Morral
Publisher:
ISBN:
Category : Dispersion strengthening
Languages : en
Pages : 214
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Author: Rointan Framroze Bunshah
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 276
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Author: John J. Burke
Publisher:
ISBN:
Category : Ceramics
Languages : en
Pages : 640
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Author: Somayeh Pasebani
Publisher:
ISBN:
Category : Ferritic steel
Languages : en
Pages : 618
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Book Description
Oxide dispersion strengthened (ODS) alloys are potential candidates to be used as high temperature structural materials in advanced nuclear and fossil energy systems because of highly stable microstructure and high creep strength. The high temperature properties of these alloys are caused by high density of dislocations and grain boundaries that are effectively pinned by ultrafine Y-Ti-O-enriched particles. The traditional processing method of ODS alloys is via mechanical alloying (MA) of high chromium content powder in combination with up to 0.5 wt.% Y2O3, followed by hot consolidation via hot extrusion or hot isostatic pressing. In the current study, Fe-based ODS and nickel-based ODS alloys are developed by using spark plasma sintering (SPS). Furthermore, in Fe-based ODS alloys or so called nanostructured ferritic steels, Y2O3 is replaced by equal atomic percent of La2O3. Then, the effects of alloying composition, processing parameters including milling parameters and sintering parameters, on the microstructure characteristics and mechanical properties of the milled powder and consolidated alloys were investigated and structure-properties were correlated. Several Fe-14Cr based alloys with varying compositions were processed. Microstructural characteristics of the consolidated alloys were examined via transmission electron microscopy and atom probe tomography, and mechanical properties were evaluated using microhardness testing, shear punch testing and mini-compression testing. Lanthanum oxide (0.5 wt.%) was added to Fe-14Cr leading for improving microstructural stability and mechanical properties mainly due to a high number density of La-Cr-O-enriched nanoclusters (NCs). The combined addition of La, Ti (1 wt.%) and Mo (0.3 wt.%) to the Fe-14Cr base composition further enhanced the microstructural stability and mechanical properties. The NCs enriched in Cr-Ti-La-O with a number density of 1.4×1024 m−3 were found in this alloy (sintered at 950 °C for 7 min) with a bimodal grain size distribution. Formation mechanism of these NCs can be explained through the concentrations and diffusion rates of the initial oxide species formed during the milling process and initial stages of sintering as well as the thermodynamics nucleation barrier and their enthalpy of formation. Milling provided solid solution, high density of dislocations, vacancies in the powder and facilitated the nucleation of NCs and enhanced the densification behavior by initiating sintering at lower temperatures while lowering the activation energy for both grain boundary and volume diffusion. Significant densification occurred at temperatures greater than 950 °C with a relative density higher than 98%. High mechanical strength values were achieved in room and high temperature are due to the combined strengthening mechanisms of work hardening, grain refinement, dispersion strengthening and solid solution strengthening. The microstructure of lanthana-bearing NFS was stable after self-ion irradiation at 500 °C up to 100 dpa. A notable irradiation hardening and enhanced dislocation activity occurred after irradiation. On the other hand, nickel-based oxide dispersion strengthened (ODS) alloys were developed by adding 1.2 wt.% Y2O3 to Ni-20Cr matrix via MA and SPS. Additionally, 5 wt.% Al2O3 was added to Ni-20Cr-1.2Y2O3 to provide composite strengthening. Higher sintering temperature led to higher fraction of recrystallized grains, higher hardness, density, and higher volume fraction of annealing twins. Adding 1.2 wt.% Y2O3 to the Ni-20Cr matrix significantly reduced the grain size. Higher compression yield stress at 800 °C for Ni-20Cr-1.2Y2O3-5Al2O3 alloy was attributed to a combined effect of dispersion and composite strengthening.
Author: United States. Wright Air Development Division
Publisher:
ISBN:
Category : Materials
Languages : en
Pages : 308
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Author: Air Force Materials Laboratory (U.S.)
Publisher:
ISBN:
Category : Materials
Languages : en
Pages : 294
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Book Description
Technical reports published by the Air Force Materials Laboratoy during the period 1 July 1962 - 30 June 1963 are abstracted herein. Reports on reseqrch conducted by the Air Force Materials Laboratory personnel as well as that conducted on contract are included. These reports cover basic and applied research in the materials area being conducted by the Metals and Ceramics Division, Non-metallic Materials Division, Materials Physics Division, Manufacturing Technology Division, and Materials Applications Division of the Air Force Materials Laboratory.
Author: Oleg D Neikov
Publisher: Elsevier
ISBN: 0080559409
Category : Technology & Engineering
Languages : en
Pages : 644
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Book Description
The manufacture and use of the powders of non-ferrous metals has been taking place for many years in what was previously Soviet Russia, and a huge amount of knowledge and experience has built up in that country over the last forty years or so. Although accounts of the topic have been published in the Russian language, no English language account has existed until now.Six prominent academics and industrialists from the Ukraine and Russia have produced this highly-detailed account which covers the classification, manufacturing methods, treatment and properties of the non-ferrous metals ( aluminium, titanium, magnesium, copper, nickel, cobalt, zinc, cadmium, lead, tin, bismuth, noble metals and earth metals).The result is a formidable reference source for those in all aspects of the metal powder industry. - Covers the manufacturing methods, properties and importance of the following metals: aluminium, titanium, magnesium, copper, nickel, cobalt, zinc, cadmium, noble metals, rare earth metals, lead, tin and bismuth - Expert Russian team of authors, all very experienced - English translation and update of book previously published in Russian
