Reduction of the oxygen content in molten metal using deoxidizers with an oxygen affinity which, at the applied reaction temperature, is higher than the oxygen affinity of the oxides to be reduced (s. Affinity) according to the following reaction (eq. 1):

Eq. 1:

In this process, the easy separation of the generated oxide from the molten metal must be ensured (slagging) and possible excessive deoxidizer must not impair the material properties.
Some aluminum alloys and aluminum-containing copper alloys, however, form non-reducible oxides at certain temperatures; thus they cannot be deoxidized so that the slag can only be removed by adding oxides to the slag.

Additional references:
Calcium carbide, Calcium silicon