Sökning: "Peierls-Nabarro model"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden Peierls-Nabarro model.

  1. 1. 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

  3. 2. 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

  4. 3. Multiscale Modeling of Interfaces

    Författare :Sven Johansson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; misfit; Peierls-Nabarro model; semicoherent interfaces; interfaces; cemented carbides; grain boundaries; microstructure; VN precipitates; density-functional theory;

    Sammanfattning : Understanding strength and stability of interfaces between dissimilar materials or phases is a highly active field of contemporary materials research. Knowledge of interface structure and energetics is important for modeling of complex materials both on a mechanical and thermodynamical level as well as for many functional properties. LÄS MER

  5. 4. Total Energy Calculations for Predictive Modeling of Crystalline Materials Strength

    Författare :Jan Hartford; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Materials properties depend on phenomena in a hierarchical order from atomic to macroscopic scales. This thesis studies possibilities for electron-structure and total-energy calculations to provide results that are valuable for the modeling of crystalline materials strength. LÄS MER

  7. 5. Hydrogen Impurities and Dislocations in Transition Metals

    Författare :Björn von Sydow; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Motion of impurities and dislocations is essential for many material properties of metals. In the present thesis we have made use of different atomistic simulation techniques to study the behavior of hydrogen and edge dislocations in transition metals. We have carried out molecular-dynamics (MD) simulations for hydrogen diffusion in niobium. LÄS MER