Magnetic, magnetostrictive and elastic behaviors of iron-binary alloys.
The addition of gallium into iron dramatically increases its magnetostriction but the exact mechanism for the magnetostriction enhancement is not clear. This research examines the influence of binary alloying elements on the magnetostriction of Fe to better understand the magnetostriction in Fe. The elements examined fall into three groups: (i) Elements with no d-shell electron (Be, Si), (ii) Elements with partially filled d-shell electron (Mo,W) and (iii) Elements with filled d-shell electron (Ge, Sn, Zn). Except for FeZn alloys, all other alloys were prepared in single crystal form using Bridgman technique. The study involved magnetostriction, saturation magnetization, and elastic moduli measurements, X-ray diffraction characterization and data analysis. Alloy compositions chosen were such that the solute content is as high as possible while retaining good magnetization levels and the single phase (alpha) structure at room temperature. Alloys examined were Fe-6 at.% Sn, Fe-15 at.% Mo, Fe-17.5 at.% Mo, Fe-4.4 at.% W, Fe-7.5 at.% W, Fe-10 at.% W, Fe-15 at.% Si, Fe-15 at.% Ge, Fe-15 at.% Be and Fe-23.5 at.% Be. Elastic properties were measured using both resonance ultrasound spectroscopy (RUS) and static compression tests. The effect of Zn addition in Fe was examined using polycrystalline Fe-x at.% Zn (x = 10 and 15) alloys prepared by powder metallurgy.; The magnetostriction constants (3/2)lambda100 in Fe-4.4 at.% W, Fe-10 at.% W and Fe-15 at.% Mo single crystals were 97 x10 -6, 122 x10-6 and 123 x10-6, respectively compared to ∼20 x10-6 for pure Fe. On a per atom addition basis, W addition leads to a larger increase in magnetostriction of Fe compared to any other non-rare-earth additions that have been examined excluding Ga. Fe-X (X = Si, Ge or Sn) alloys exhibit much lower magnetostriction values than those observed in FeGa alloys. This may be attributed to the additional p electron in these elements compared to Ga that promotes more bonding. Only a minor influence of Zn on the magnetostriction of Fe was observed. Magnetostriction in FeBe alloys with Be contents of 15 at.% and 23.5 at.% are much lower than that reported for Fe-6 at.% Be and Fe-11 at.% Be, and this likely results from a second phase precipitation.......
【作者单位】: The University of Utah.
【关 键 词】: Magnetic
, magnetostrictive and elastic behaviors of iron-binary alloys.
【授予学位单位】: The University of Utah.
【学科】: Engineering, Metallurgy.
【上篇论文】: 学术学位 - Heat treatment and mechanical properties of aluminum-silicon modified alloys.
【下篇论文】: 学术学位 - Plastic instabilities due to material rotation and texture.