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Projecte llegit

Títol: Crystallization study on CuZr metallic glasses

Estudiants que han llegit aquest projecte:

Director/a: BRUNA ESCUER, PERE

Departament: FIS

Títol: Crystallization study on CuZr metallic glasses

Data inici oferta: 08-07-2013     Data finalització oferta: 08-03-2014


Estudis d'assignació del projecte:
    GR ENG SIS TELECOMUN
    GR ENG TELEMÀTICA
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Metallic glasses, Crystallization
 
Descripció del contingut i pla d'activitats:
Glasses are solid materials characterized by their lack of long
range order, that is, solids with a liquid-like structure.
Besides the common silica-based glasses conventionally used in
windows, glasses obtained with metallic elements can also be
produced, the so-called metallic glasses (MGs). Metallic glasses
can only be produced from the melted alloy using a extremely high
cooling rate (of the order of 106 K/s), thus limiting the
metallic compositions that are able to become glasses. The CuZr
system is particularly useful because it can form glasses in a
wide range of compositions, from 20 at.% Cu to 80 at% Cu. In
order to study the transition from liquid to glass (the glass
transition) it is useful to study the atomic dynamics of the
glass and compare it with the atomic dynamics of a similar
crystal. The problem with metallic glasses is that the initial
amorphous phase usually have a different stochiometry than the
crystal produced from this phase after a particular heat
treatment, thus making the comparison impossible. Moreover, the
final crystallization products usually contain more than one
phase and then its dynamics is a mixture of the crystal dynamics
of these several phases. The aim of this project is to find a
CuZr composition able to produce a glass that crystallize in a
single phase with the same stochiometry than the original glass.
To do that, a study of the phase diagram for the CuZr system will
be studied and according to it the compositions will be selected.
After that, the metallic glasses will be produced using the arc
melter and melt spinning technique and the resulting glasses will
be thermally characterized using Differential Scanning
Calorimetry. Finally, the glasses will be crystallized and X-Ray
Diffraction will be used to identify the crystalline phases and
compare them with the original amorphous structure.

As a second objective of the project, several glasses of the CuZr
system will also be produced but using non-pure Cu obtained from
industrial residues. The purpose of this objective is to
demonstrate that metallic glasses can be obtained using raw
elements without 99.99 at% purity, thus reducing the costs of
fabrication. This fact together with the possibility of recycle
industrial residues increase the economic viability of metallic
glasses and it could extend the range of applicability of this
type of materials.
 
Overview (resum en anglès):
Glasses are solid materials characterized by their lack of long
range order, that is, solids with a liquid-like structure.
Besides the common silica-based glasses conventionally used in
windows, glasses obtained with metallic elements can also be
produced, the so-called metallic glasses (MGs). Metallic glasses
can only be produced from the melted alloy using a extremely high
cooling rate (of the order of 106 K/s), thus limiting the
metallic compositions that are able to become glasses. The CuZr
system is particularly useful because it can form glasses in a
wide range of compositions, from 20 at.% Cu to 80 at% Cu. In
order to study the transition from liquid to glass (the glass
transition) it is useful to study the atomic dynamics of the
glass and compare it with the atomic dynamics of a similar
crystal. The problem with metallic glasses is that the initial
amorphous phase usually have a different stochiometry than the
crystal produced from this phase after a particular heat
treatment, thus making the comparison impossible. Moreover, the
final crystallization products usually contain more than one
phase and then its dynamics is a mixture of the crystal dynamics
of these several phases. The aim of this project is to find a
CuZr composition able to produce a glass that crystallize in a
single phase with the same stochiometry than the original glass.
To do that, a study of the phase diagram for the CuZr system will
be studied and according to it the compositions will be selected.
After that, the metallic glasses will be produced using the arc
melter and melt spinning technique and the resulting glasses will
be thermally characterized using Differential Scanning
Calorimetry. Finally, the glasses will be crystallized and X-Ray
Diffraction will be used to identify the crystalline phases and
compare them with the original amorphous structure.

As a second objective of the project, several glasses of the CuZr
system will also be produced but using non-pure Cu obtained from
industrial residues. The purpose of this objective is to
demonstrate that metallic glasses can be obtained using raw
elements without 99.99 at% purity, thus reducing the costs of
fabrication. This fact together with the possibility of recycle
industrial residues increase the economic viability of metallic
glasses and it could extend the range of applicability of this
type of materials.

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