Sökning: "Invar alloys"

Visar resultat 1 - 5 av 7 avhandlingar innehållade orden Invar alloys.

  1. 1. On the hot crack formation during solidification of iron-base alloys

    Författare :Karin Hansson; KTH; []
    Nyckelord :hot cracking; hot tearing; cracking fracturing ; tearing; ductility; brittleness; embrittlement; fractures; ductile brittle transition; solidification; iron; copper; nickel; Invar; steels; free machining steels; stainless steels; penetration; crack;

    Sammanfattning : Hot cracking during solidification is a severe problem inmany casting processes, for example in continuous casting.Combinations of low strength and low ductility of the materialat high temperatures and applied tensile stress can cause hotcracking. LÄS MER

  3. 2. Influence of Global Composition and Local Environment on the Spectroscopic and Magnetic Properties of Metallic Alloys

    Författare :Weine Olovsson; Igor A. Abrikosov; G. Malcolm Stocks; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; core level shift; random alloy; first principles simulations; density functional theory; auger kinetic energy; Invar alloys; exchange parameter; classical Heisenberg Hamiltonian; complete screening; transition state; disorder broadening; Fysik; Physics; Fysik;

    Sammanfattning : Theoretical investigations of spectroscopic and magnetic properties of metallic systems in the bulk, as well as in nanostructured materials, have been performed within the density functional theory. The major part of the present work studies the differences between binding energies of electrons tightly bound to the atoms, the so-called core electrons (in contrast with the valence electrons), that is, core-level binding energy shift (CLS). LÄS MER

  4. 3. Mössbauer Spectroscopy of Meteoritic and Synthetic Fe-Ni Alloys

    Författare :Yassir Ahmed Mohamed Abdu; Hans Annersten; Tore Ericsson; Johan Linden; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Meteorites; Tetrataenite; Antitaenite; Mössbauer spectroscopy; Mechanical alloying; Fe-Ni alloys; High pressure; Geovetenskap; Earth sciences; Geovetenskap; mineralogi; petrologi och tektonik; Mineral Chemistry; Petrology and Tectonics;

    Sammanfattning : This thesis reports on the results of investigating Fe-containing minerals in meteorites, with focus on Fe-Ni minerals and their magnetic properties, along with some synthetic Fe-Ni analogues. The New Halfa meteorite, which fell in Sudan 1994, has been studied using Mössbauer spectroscopy, X-ray diffraction, and electron microprobe analysis techniques, and classified as an ordinary L-type chondrite of petrologic type 4. LÄS MER

  5. 4. First-principles study of spin-flip transition in Fe-Ni invar alloys

    Författare :François Liot; Linköpings universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : More than a hundred years ago, Guillaume discovered that the alloy Fe65Ni35, at equilibrium under normal pressure, was invar. Indeed, its thermal expansion coefficient was anomalously small over a wide temperature interval. It is now known that the invar effect in this alloy is related to magnetism. LÄS MER

  7. 5. Thermal Expansion and Local Environment Effects in Ferromagnetic Iron-Based Alloys : A Theoretical Study

    Författare :François Liot; Igor Abrikosov; Peter Mohn; Linköpings universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : The Nobel Prize for Physics 1920 was awarded to C.-E. Guillaume for his discovery of properties of nickel steels. He had previously observed that certain iron-nickel alloys exhibit the Invar effect i. LÄS MER