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| 2. |
- Razumovskii, I. M., 1985-, et al.
(författare)
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Effect of the Particle Size of γ’ Phase on the Mechanical Properties of Ni base Superalloy
- 2011
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Ingår i: Euro Superalloys 2010. - : Trans Tech Publications Inc.. - 9783037851135 ; , s. 96-101
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Konferensbidrag (refereegranskat)abstract
- The effect of gamma’ particle size upon the mechanical properties of Ni base superalloy EP741NP obtained by powder metallurgy was investigated. The particle size of gamma’ phase in gamma-gamma’ microstructure was varied by changing the cooling rate V from the temperature of the solid solution treatment at 1200 C (V = 80, 200 and 400 C \ min.). After solid solution treatment billets were subjected to aging in the standard mode. It was established that as V increases from 80 to 200 C \ min., the average particle’s size of gamma’ phase decreases from 0.54 microns to 0.22 microns in the aged state. This improves the characteristics of creep and low cycle fatigue at 650C: time to rupture under load 1000 MPa increased from 132 hours to 416 hours and low cycle fatigue increased from 42,215 to 82,016 cycles.
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| 3. |
- Razumovskii, I. M., et al.
(författare)
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New generation of Ni-based superalloys designed on the basis of first-principles calculations
- 2008
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 497:1-2, s. 18-24
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Tidskriftsartikel (refereegranskat)abstract
- A new approach to the design of Ni-based single crystal superalloys is proposed. It is based on a concept that under given structural conditions, the creep-rupture characteristics of superalloys are mainly determined by interatomic bonding given by the cohesive energy. In order to characterize the individual contribution of each alloying element to the strength properties at high temperature, we introduce a parameter, X, which is the partial molar cohesive energy of an alloy component. This parameter is then obtained in the total energy first-principles calculations for a usual set of alloying elements. We demonstrate that creep-rupture characteristics of alloys indeed correlate with the total gain partial molar cohesive energy due to alloying and find that W, Ta, and Re have the highest values of X, and should therefore play the major role in providing high-temperature strength of superalloys. Based on this finding, we design three new superalloys with a high content of W and show that they have superior creep-rupture properties compared not only with their counterparts with the lower content of W, but also with the best Ru-bearing Ni-based superalloys.
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| 4. |
- Razumovskiy, Vsevolod I., 1985-, et al.
(författare)
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Analysis of the Alloying System in Ni-Base Superalloys Based on Ab Initio Study of Impurity Segregation to Ni Grain Boundary
- 2011
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Ingår i: EURO SUPERALLOYS 2010. - : Trans Tech Publications Inc.. - 9783037851135 ; , s. 192-197
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Konferensbidrag (refereegranskat)abstract
- A new approach to the design of Ni-based polycrystalline superalloys is proposed. It is based on a concept that under given structural conditions, the performance of superalloys is determined by the strength of interatomic bonding both in the bulk and at grain boundaries of material. We characterize the former by the cohesive energy of the bulk alloy, whereas for the latter we employ the work of separation of a representative high angle grain boundary. On the basis of our first principle calculations we suggest Hf and Zr as “minor alloying additions” to Ni-based alloys. Re, on the other hand, appears to be of little importance in polycrystalline alloys.
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| 5. |
- Razumovskiy, Vsevolod I., 1985-, et al.
(författare)
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Effect of Alloying Elements and Impurities on Interface properties in Aluminum Alloys
- 2011
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Ingår i: Physics of the solid state. - 1063-7834 .- 1090-6460. ; 53:11, s. 2189-2193
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Tidskriftsartikel (refereegranskat)abstract
- The segregation energies of B, Si, P, Cr, Ni, Zr, and Mg on the special grain boundary (GB) Σ5 (210)[100] and on the open (210) surface of aluminum have been determined and the GB splitting energy has been calculated by the density functional theory methods. It has been shown that all elements listed above enrich the GB; for B, Si, P, Cr, Ni and Zr, Mg, interstitial and substitutional sites are preferred, respectively. The effect of alloying elements on the GB binding has been estimated using the parameter η equal to the change in the fracture work of the aluminum GB when adding alloying element atoms. From the viewpoint of strengthening the GB binding forces, Zr, Cr, Ni, and Mg are efficient, Si and B are neutral and phosphorus weakens GBs.
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| 6. |
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| 7. |
- Razumovskiy, Vsevolod I., et al.
(författare)
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The effect of alloying elements on grain boundary and bulk cohesion in aluminum alloys : An ab initio study
- 2011
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 65:10, s. 926-929
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Tidskriftsartikel (refereegranskat)abstract
- The effect of B, Si, P, Cr, Ni, Zr and Mg impurities on cohesive properties of Al and its special grain boundary (GB) Sigma 5 (2 1 0) [1 0 0], as well as their segregation behavior at the GB and (2 1 0) surface are studied from first principles. Our analysis determines Ni to be the best and P the worst alloying elements in regard to the overall resistance to decohesion of Al alloys.
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| 8. |
- Razumovskiy, Vsevolod I., 1985-, et al.
(författare)
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The influence of alloying elements on grain boundary and bulk cohesion in aluminum all : Ab initio study
- 2012
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Ingår i: Thermec 2011 Supplement. - : Trans Tech Publications Inc.. - 9783037853047 ; , s. 417-422
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Konferensbidrag (refereegranskat)abstract
- The effect of B, Si, P, Cr, Ni, Zr and Mg on cohesive properties of Al and the specialgrain boundary (GB) Σ5 (210)[100], as well as their segregation behavior at the GB and the (210)surface are studied by first principles method. The analysis of these parameters allows us to singleout Ni as the best and phosphorus as the worst interatomic bond strengthening alloying elements.
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