dc.contributor |
Universitat Politècnica de Catalunya. Departament de Física Aplicada |
dc.contributor |
Crespo Artiaga, Daniel |
dc.contributor.author |
Facchini, Laura Serena |
dc.date |
2008-06-20 |
dc.identifier.uri |
http://hdl.handle.net/2099.1/4985 |
dc.language.iso |
eng |
dc.publisher |
Universitat Politècnica de Catalunya |
dc.rights |
Attribution-NonCommercial-ShareAlike 2.5 Spain |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.rights |
http://creativecommons.org/licenses/by-nc-sa/2.5/es/ |
dc.subject |
Àrees temàtiques de la UPC::Enginyeria de la telecomunicació |
dc.subject |
Metallic glasses |
dc.subject |
Bulk metallic glasses |
dc.subject |
Melt spinning |
dc.subject |
X-Ray diffraction |
dc.subject |
Mössbauer spectroscopy |
dc.subject |
Electron microscopy |
dc.subject |
Viscoelasticitat -- Materials |
dc.subject |
Viscoplasticitat |
dc.title |
Production and characterization of Fe-based metallic glasses |
dc.type |
info:eu-repo/semantics/masterThesis |
dc.description.abstract |
Amorphous metallic alloys were developed at 1960. Since then, scientists have
not stopped researching in order to improve their properties and find new
applications. The innovation in techniques has let to the creation of functional
structural materials with unknown properties until now, that have certain
properties that could be of great utility for engineering applications.
The aim of this project is to produce three amorphous steel alloys, Fe71.2-x
C7.0Si3.3B5.5P8.7Cr2.3Al2.0Mox (x=0, 4.5 and 6.5 at%) by the melt-spinning
technique. This work presents a detailed description of the basic equipment to
produce these ribbons.
The Fe-based metallic glasses were then characterized by electronic
microscopy and X-ray diffraction that allow us to know the real composition of
the ribbons and if the atomic structure is or is not amorphous. Transmission
Mössbauer spectroscopy (TMS) allows us to study the local environments of the
Fe atoms in the glassy state, showing the changes in the amorphous structure
due to the addition of Mo. A reduction of the mean hyperfine field is observed as
the amount of Mo increases. Moreover the three alloys were studied with
differential scanning calorimetry (DSC) to find the glass transition temperature
and to decide the suitable temperature of the heat treatments to relax the
glasses. Finally, the relaxed samples were analized again with TMS in order to
see the stability of the alloys and the effect of the local structure changes.
The main conclusions reached during the project can be summarized as follows.
In the alloys with intermediate Mo content, the hyperfine field reduction is
associated to the substitution of Fe by Mo in a disordered magnetic Fe-rich
structure, whereas for the alloys with high Mo content, this structure is destroyed
leading to an increase of paramagnetic environments. The relationship between
the GFA of these alloys and their local structure determined by TMS is
discussed. |