One Response to “Conductivity/ductility relation?”

1. admin says:

   March 1 at 7:56 am

   jndbe…@scilab.uct.ac.za wrote:
   >Does anybody have any references to ( maybe ) a theory explaining the
   >relation between ductility/conductivity?

   Are you talking about electrical conductivity or thermal conductivity?
   Diamonds and some carbon fibers have terrific thermal conductivity and
   essentially no ductility.  High temperature semiconductors have *very
   large* electrical conductivity but are extremely brittle.  A number of
   superalloys based on cobalt or nickel are quite ductile, but not very
   conductive; same with some austenitic stainless steels.  

   >    Au  very ductile,conductive
   >    Cu  very conductive,ductile
   >    Ag  very ductile,conductive
   >    Fe  baddish conductivity,brittle ( cast iron )
   >    Pb  baddish conductivity,not ductile ( but malleable )

   Cast iron isn’t very pure iron.

   In metals, high defect density tends to reduce both ductility and
   conductivity but in a given alloy the effect on ductility is much greater
   than on conductivity.  Have you ever read about the experiment (I don’t
   recall exactly where I read about it) where diamond was made with a single
   carbon isotope (C-12 only) and the thermal conductivity was found to be
   much greater than in natural diamond?  Another intriguing phenomenon is
   the relation between conductivity (both thermal and electrical) and purity
   in substitutional alloy systems, such as copper/nickel.  Conductivity
   peaks at the pure metals and drops orders of magnitude for mixtures.

   >Or, better still, can someone mail me anything relevant?
   >We’ve discovered this in a recent lecture, checked some encyclopaedias,
   etc.
   >but no text we’ve had so far connect the two.

   I think the problem invariably involves quantum mechanics at the very deep
   hand-waving level. [:<8)]

   Mark Folsom