| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- Razumovskiy, Vsevolod I., 1985-, et al.
(författare)
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Ab-initio calculations of kinetic properties in ZrC and TiC carbides
- 2011
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Konferensbidrag (refereegranskat)abstract
- Self-diffusion of the metal and carbon atoms in TiC and ZrC carbides is studied by first principles methods. Our calculations yield point defects energies, vacancy jump barriers and diffusion pre-factors in TiC and ZrC. The results are in reasonable agreement with the available experimental data and suggest that the self-diffusion mechanism for metal atoms in these carbides may involve nearest-neighbor vacancy pairs (one metal and one carbon vacancy).
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| 6. |
- Razumovskiy, Vsevolod I., 1985-, et al.
(författare)
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Effect of temperature on the elastic anisotropy of pure Fe and Fe0.9Cr0.1 random alloy
- 2011
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 107:20
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Tidskriftsartikel (refereegranskat)abstract
- The elastic properties of pure iron and substitutionally disordered 10 at. % Cr Fe-Cr alloy areinvestigated as a function of temperature using first-principles electronic-structure calculations bythe exact muffin-tin orbitals method. The temperature effects on the elastic properties are includedvia the electronic, magnetic, and lattice expansion contributions. We show that the degree ofmagnetic order in both pure iron and Fe90Cr10 alloy mainly determines the dramatic change of theelastic anisotropy of these materials at elevated temperatures. The effect of lattice expansion isfound to be secondary but also very important for quantitative modeling.
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