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in the aluminium matrix, that means<br />
the nanotubes are still there after hot<br />
extrusion, they are not converted into<br />
carbi<strong>de</strong>s. The properties of this new<br />
materials are very impressive in stabilizing<br />
hardness. A pow<strong>de</strong>r without<br />
CNT showed a high hardness of HV<br />
270, but after extrusion the material is<br />
softening by grain growth to 140 HV.<br />
With the CNT addition the values after<br />
hot extrusion don’t fall as sharply: 3 %<br />
CNT brought a hardness of 210 HV<br />
after extrusion, caused by a crystallite<br />
size stabilisation. 9 % brought a value<br />
of 270, however then the materials is<br />
“brittle like ceramics”. But in the area<br />
between 3 and 6 % there is enough<br />
ductility, but also a high hardness. It is<br />
necessary and possible to find the optimum,<br />
the speaker said and explained<br />
the secret of a new light metal: “We<br />
don’t have to use lithium, we only use<br />
a little bit of our won<strong>de</strong>rdust”. The next<br />
step will be to increase the elongation.<br />
Adams mentioned: “4 % is enough to<br />
METALL | 63. Jahrgang | 5/2009<br />
do some forming, but we still want to<br />
have more.”<br />
Second Secret: Proper conditions<br />
Prof. Dr. Henning Zoz discussed commercial<br />
goals for nanostructures and<br />
green composites. He said: „Not long<br />
time ago nobody would have believed<br />
that a technique like mechanical alloying<br />
(MA) which shall here also be<br />
the pseudonym for high energy and<br />
reactive milling (HEM and RM) could<br />
be a key factor for commercial manufacturing<br />
of nanostructured materials<br />
on a large scale.” He spoke about some<br />
problems in this process (e.g. long<br />
time, contamination...) and showed:<br />
“If the processing techniques MA, RM<br />
and HEM which can be conclu<strong>de</strong>d<br />
as high kinetic processing (HKP) are<br />
applied un<strong>de</strong>r proper conditions, this<br />
can be completely different.“ Proper<br />
conditions here mean a transfer of kinetic<br />
energy un<strong>de</strong>r high kinetic energy<br />
G L Ü H E N I M G R O S S E N S T I L !<br />
Von Spannungsarmglühen, Weichglühen, Homogenisieren,<br />
Normalisieren bis hin zum Luftvergüten … Wir<br />
bringen Ihre Produkte wärmetechnisch auf Vor<strong>de</strong>rmann!<br />
Die Wärmebehandlungen wer<strong>de</strong>n im Lohn im Bereich<br />
von 300 – 1.000 °C, insbeson<strong>de</strong>re für größere Glühgüter<br />
bis 14,40 m Länge, 4,20 m Breite, 3,00 m Höhe und<br />
bis zu 100 t Einzelgewicht durchgeführt. Anzeige Gebr. Löcher<br />
Für Stahl und NE-<strong>Metall</strong>e, z. B. Aluminium, Kupfer,<br />
Messing und Titan, sowie Eisenwerkstoffe. TÜV-zugelassene<br />
Ofenanlagen, Werkstoffkompetenz und hohe<br />
Temperaturgenauigkeiten run<strong>de</strong>n Ihr Anfor<strong>de</strong>rungsprofil<br />
ab.<br />
Gebr. LÖCHER Glüherei GmbH<br />
Mühlenseifen 2, 57271 Hilchenbach<br />
Tel. 02733-8968-0 Fax. 02733-896810<br />
Email: info@loecher-glueherei.<strong>de</strong><br />
www.loecher-glueherei.<strong>de</strong><br />
METALL VOR ORT<br />
Prof. Dr. Henning Zoz, Zoz Group (right) and<br />
Rainer Lindau (Kernforschungszentrum<br />
Karlsruhe)<br />
215
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