WE ARE ALLOYING A SMALL PERCENTAGE (0.3%) OF ZIRCONIUM METAL  WITH
COPPER WHICH IS HEATED TO ABOUT 1200 C.
THE PROCESS IS CARRIED OUT IN A VACUUM WITH DEOXIDIZED COPPER BUT WE
ARE STILL LOSING OVER 50% OF THE ZIRCONIUM ADDITION. IT IS ALSO
REPORTED THAT THE REFRACTORY IN THE CRUCIBLE ERODES FASTER WHEN THESE
ZIRCONIUM HEATS ARE MADE . WILL PURE ZR REACT WITH THE CLAY GRAPHITE
MATERIALS( MAY CONTAIN SILICON OXIDES)IN THE CRUCIBLE TO PRODUCE
ZIRCON? WHAT ALTERNATE REFRACTORY CAN I USE IN THE CRUCIBLE

At high temperatures, Zr metal will react with carbon (i.e., the
graphite in your crucible) to form zirconium carbide (ZrC).  Ther's a
good chance that this is what is happening in your situation.  Under
the reducing conditions present in your crucible, it is unlikely that
the Zr will form silicates.

Melts containing reactive metals like Ti, Hf, and Zr are challenging,
because they will react with most crucible materials.  You might look
into using a ceria-yitria coated crucible, or going with cold-wall
crucible/melter technology.