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Profile
Aluminium grains are tiny. There are as many in one cubic
millimetre as there are sand grains on a beach. In working
with these aluminium grains, SIMLab realized that they
needed to learn more about the details inside the grains.
There were indications that lower scale matters. The logical
consequence is that studies down to atomic level are needed
to establish material properties with greater certainty.
Studying details in the microstructure - such as particles,
precipitates, dislocations and grain boundaries - gives a
better understanding. This in turn will help with experiments,
simulation and modelling as basis for innovation.
THE MICROSCOPE
Enter Professor Holmestad and her team at NTNU’s Department
of Physics. They possess a NOK ~20 million state-of-the-art
transmission electron microscope (TEM) allowing studies down
to 0.06 nanometre. The distance between atoms in materials
is in the order of 0.2 nanometres, so only now will the
researchers be able to study in detail what happens to the atom
structure when the materials are subjected to impacts such
as collisions and explosions. The same goes for temperature
changes. One of the many areas where such knowledge will
become increasingly important is operating oil rigs in Arctic
waters.
RANDI RUNS
Randi Holmestad runs. Literally. If colleagues observe her
walking in the corridor, they will pop out of their office and ask
if something is wrong.
Running can bring you pretty far. In 1998, at 30, Randi became
the youngest female professor in the university. A few years
later, her supervisor fell ill and she had to step up as group
leader. Since then she has guided 52 master’s students and
13 PhD candidates through thick and thin. Two years ago
her department acquired the world class microscope as part
of the NORTEM large scale infrastructure project, where
NTNU collaborates with SINTEF and the University of Oslo.
Starting now, SFI CASA will be able to share the benefits. Emil
Christiansen, the first PhD candidate on this task, is already
working on this with a thesis on precipitate microstructures.
KNOWS ALUMINIUM
If Professor Holmestad is new to CASA, she is by no means new
to aluminium or to external partners. Norwegian aluminium
producer Hydro has a decades-long relationship with NTNU’s
Department of Physics and depends on its scientific results
to keep up front. Part of the current cooperation through the
“Hydro Road Map” scheme was developed in the tripartite
relation between Hydro, SINTEF and NTNU. CASA director
Magnus Langseth was one of the creators. Holmestad is one
of many contributors and is the proud holder of a patent on an
aluminium alloy.
“I feel privileged for taking part. This kind of long-term
cooperation has huge, mutual benefits,” she says.
Likewise, she has cooperated with CASA research partner
SINTEF for years and years. She thoroughly enjoys the
exchange:
“It’s rewarding when partners like Hydro, Benteler and SAPA
need input.”
USEFUL NEEDLES
In its pure form, a piece of aluminium is bendable with pure
manpower. The application value starts when alloying with
silicon, magnesium, zinc, copper, silver, germanium and other
metals, where only a per cent or two dramatically changes the
characteristics of the material. In age hardenable aluminium
alloys this is due to nano-sized precipitates – small needles
precipitating all over the place in the alloy, which you can
observe in the microscope. As is the case for any cake in the
oven, time and temperature are crucial factors.
In Holmestad’s case, she admits a special weakness for one of
the alloying atoms:
“I’m particularly fascinated by the copper atoms.”
At the moment, Holmestad is working on a project that seeks to
reduce the alloying content of extruded and rolled aluminium
without loss of strength.
“By smart alloy design, we can reduce the total solute, the
alloys can be easier processed and Hydro saves money.”
AS FAR AS NECESSARY
Holmestad’s role in CASA will be to go as far down in detail as
necessary, not further. She and her collaborators will try to
establish what is needed to make more suited materials for
any given purpose; be it construction details that might be
applicable in the new government administration complex in
Oslo, a car part or another industrial application.
With time, the findings will be added to the SIMLab Tool Box
for the partners to use.
FAITHFUL
CASA’s newly recruited professor has remained faithful to
Trondheim and NTNU throughout her career, with the exception
of four half-year visits to US universities in Arizona and Illinois.
She’s run since childhood. Early on she was attracted to
orienteering. Now she’s taken up the activity, but at a more
modest level. And of course, she still runs in the corridors.
New Girl on the
BLOCK
The folks at SIMLab know better than anyone how aluminium grains behave under attack.
Because of that, they decided that the follow-up - CASA - needs expertise on
atomic level. Randi Holmestad’s expertise.