Nanoparticles Induced Superplasticity in a Colloidal Metal.
Tutors : D. Roux, MdC UJF (HDR), F. Caton, CR1, CNRS,
Email : denis.roux@ujf-grenoble.fr catonf@ujf-grenoble.fr tél : 04 76 82 51 67
PhD extension: Yes.
Many every day life materials are made of cristalline
aggregates (polycristals) where the cristalline grains are
separated by Grain Boundaries (GB).The slip and migration of
the GB play major roles in the plastic deformation and fracture
of these materials, which control their processing ability as well
as their shelf life. Besides, it is known from the antiquity that
the addition of soot (carbon nanoparticles) increases
considerably the plasticity of metals, generating a behaviour
that is now coined as "superplasticity".
This superplasticity allows cold forming of metals
which is much less energy hungry and thus environment frindly
than hot forming. However, the mechanisms of superplasticty
are yet far from understood, mainly because of the opacity of
metals to all light and synchrotron radiations. To remove this
major lock, we use an exact colloidal analog of a metal,which
has the hudge advantage of being transparent. We expect to cellular organisation of nanoparticules at the
produce unprecedented informations both space and time grain boundaries of the colloidal metal
(confocal microscopy). The average size of
resolved during the deformation of the material
the grains is 30 m
The proposed research project consists in linking the macroscopic behaviour of the material during shearing to
the nanoscopic dynamics using a new method coupling rheometry and a multispeckles technique.