Hi Richard! There should be a specification/requirement in terms of how to 
measure that temperature and the tolerance of the temperature measurement 
on where the Liquidus and Solidus coincide. My guess is that it is a IEC, 
NIST or ASTM specification  but I don't have any specifics (maybe DSC test 
method specifics?). If Carol Handwerker at Purdue or Maureen Williams at 
NIST are  watching the TechNet discussion, they may be able to point us in 
the right direction. 
Dave



"Stadem, Richard D." <[log in to unmask]> 
05/23/2007 09:23 AM

To
"TechNet E-Mail Forum" <[log in to unmask]>, <[log in to unmask]>
cc

Subject
RE: [TN] Definition of Eutectic Solder






Dave/Werner,
In all of these discussions of the term eutectic alloy, I always
wondered if there was a concrete definition of eutectic. Is there a
specification or standard that determines the plus/minus temperature
range over which an alloy transcends through the completely liquified
stage to the completely solidified stage in order to be called
"eutectic"?
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Wednesday, May 23, 2007 8:36 AM
To: [log in to unmask]
Subject: Re: [TN] Definition of Eutectic Solder

Hi Werner! Here is the definition from the American Society for Metals
(ASM) Metals Handbook, 2nd Edition:

"Eutectic. (1) An isothermal reversible reaction in which a liquid
solution is converted into two or more intimately mixed solids on
cooling, the number of solids formed being the same as the number of
components in the system"

Now, your definition is perfectly correct too and I agree with it. 
However, using the terms Liquidus and Solidus are necessary in the
definition. Most folks struggle a bit  with the terms Liquidus or
Solidus and I didn't want to get too deep in the metallurgy (Mr. Pauls
has such a hard time understanding metals and the English language in
general  (if folks haven't noticed,  Doug and I are making fun of each
other today). 

Lots of fun metallurgy discussions to start the day! Very cool.

Dave



Werner Engelmaier <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
05/23/2007 08:03 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
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Subject
Re: [TN] Definition of Eutectic Solder






Hi Dave,
Sorry, I must disagree; your definition of "1) Eutectic: when a metal 
alloy 
transforms from a liquid state into a
single solid state" is wrong.
A eutectic alloy composition is by definition that composition where the

alloy's Solidus and Liquidus temperatures coincide and having the lowest

melting 
temperature among all other alloy compositions of the same materials.

Werner



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