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eutectics, phase diagrams and the melt space--another reply to dan

updated tue 13 feb 07


Dave Finkelnburg on sun 11 feb 07

This is an important point. Yes, strictly speaking
you have stated precisely what a eutectic is.
IF I recall my phase diagrams correctly, it is also
possible to have more than one eutectic. What this
means is simply that as one maps the melting points of
the infinite number of possible compositions of, say 2
(for simplicity but it works for N) materials, it is
possible to find more than one composition for which
the melting point of materials to either the left or
right of it on a 2-D graph are at higher temperatures.
If you look at the potash-alumina-silica phase diagram
you will see two on the edge of the potash feldspar
phase field.
Good potting,
Dave Finkelnburg

From: Dan Semler
As I understand it, a eutectic is
the lowest melting point composition of, say 2 (or N)
materials. The
fact that two components in any proportions will melt
at a lower
temperature than either alone, does not define a
eutectic. Rather it
is the specific composition of the, say 2, materials
that give the
lowest melting point, that is the eutectic. Is my
understanding on
this point correct ?

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