tungsten alloys for SG electrodes?

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Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi all,

I'm currently in the process of trying to source some rod stock
tungsten for electrodes for an RSG. I noticed that McMaster-
Carr has some tungsten alloy as well as tungsten carbide in
rod form and I was wondering about the suitability of these ma-
terials for SG electrodes for a high powered coil system. I noticed
that the "high-density tungsten alloy" is a 90% tungsten/ 6%
nickel/ 4% copper alloy and is machinable. It also states that
the melting point is a mere 2012*F. Is that a misprint? Surely a
90% tungsten alloy would have a much higher melting point than
that, since the melting point of pure tungsten is like 6170*F!
Maybe that was suppose to read 2012*C instead of Farenheit?

Also, how suitable would tungsten carbide be for rotary elec-
trodes, as far as heat & electrical conductivity is concerned?
I remember reading some of the late Marc Metlica's posts re-
garding use of tungsten carbide for SG electrodes. He had
easy access to tungsten carbide because of some of his tool-
ing supplies and he really liked using the carbide for this pur-
pose. I know that tungsten carbide is extremely hard though
and almost impossible to machine without special diamond
tipped cutting tools, so I would prefer to use the high density
tungsten alloy (90/6/4 - tungsten/nickel/copper percentage)
if possible, since it's much easier to machine and is available
in the 3/8" to 1/2" range that I'm looking for. Any comments
from the more metallurgicaly inclined would be welcome :^)))

David Rieben