Sökning: "Coarsening"

Visar resultat 6 - 10 av 58 avhandlingar innehållade ordet Coarsening.

1. 6. Theoretical studies of boron and transition-metal carbonitride additions in steels

   Författare :Dan Fors; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Electronic structure; Dislocation network; Interfaces; Peierls-Nabarro model; Density functional theory; Steels; Coarsening; Diffusion; Misfit; Precipitates;

   Sammanfattning : Martensitic 9-12%Cr steel alloys are today widely used as critical components in fossil-fired steam power plants with steam temperatures up to 600°C, where sound oxidation resistance and excellent creep strength are required. Their strength and long-term creep resistance are closely connected to the presence and stability of Cr-rich M23C6 (M = Cr, Fe) carbides and densely distributed MX precipitates (M = transition metal, X = C or N), which effectively act as obstacles for dislocation migration. LÄS MER

3. 7. Precipitate stability in creep resistant 9-12% chromium steels

   Författare :Ardeshir Golpayegani; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; growth; precipitates; coarsening; atom probe field ion microscopy APFIM ; energy filtered TEM EFTEM ; 9-12% chromium steel;

   Sammanfattning : 9-12% chromium steels are used extensively in modern steam power plants at service temperatures up to 600°C. These materials are subjected to creep deformation during exposure which is the limiting factor in increasing the steam temperature and thus the thermal efficiency of the plants. LÄS MER

4. 8. Toward first-principles understanding of carbonitride precipitation in steels

   Författare :Dan Fors; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Steels; Coarsening; Interfaces; Peierls-Nabarro model; Diffusion; Precipitates; Density functional theory; Dislocation network; Misfit; Electronic structure;

   Sammanfattning : The most important and widely used group of metallic alloys is steels, whichare alloys of the element iron together with carbon and usually other elementssuch as B, N, V, Nb and Cr. The strength in these alloys is closely connectedto the distribution of point defects, precipitates and grain boundaries whicheffectively act as obstacles for dislocation migration. LÄS MER

5. 9. Development of a new generation of creep resistant 12% chromium steels: Microstructure of Z-phase strengthened steels

   Författare :Masoud Rashidi; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; phase transformation; CrNbN; impact toughness; Creep; CrTaN; Laves-phase; atom probe tomography; precipitation hardening; M2N; MX; transmission electron microscopy; coarsening;

   Sammanfattning : Fossil-fuel fired steam power plants provide more than 60% of the electricity generated worldwide, and account for about one third of the global CO2 emissions. Increasing the steam temperature and pressure leads to a higher thermal efficiency of the power plants and thus lower emissions. LÄS MER

7. 10. Structure evolution of phase-separated EC/HPC films for controlled drug release

   Författare :Pierre Carmona; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; electron microscopy; coarsening; cellulose; phase separation kinetics; drug delivery; phase separation mechanisms; porous film; biopolymer; controlled drug release; confocal laser scanning microscope; spin-coating.;

   Sammanfattning : Porous phase-separated ethylcellulose/hydroxypropylcellulose (EC/HPC) films are used to control drug transport out of pharmaceutical pellets. The drug transport rate is determined by the structure of the porous films that are formed as the water-soluble HPC leaches out. LÄS MER