Thixoforming : Semi-solid Metal Processing

142j 4 Design of Al and Al–Li Alloys for Thixoforming
Figure 4.30 Experimental K contents in the metal after treatment
of AlLi4Mg4 and AlLi4Cu4 melts using KCl–LiCl salt mixtures
at 750 C.
Figure 4.31 Almost closed-loop recycling of AlLi residues.
The tests using a salt mixture of KCl and LiCl for melting residues from AlLiMg
and AlLiCu did, however, indicate that it is possible to retain the Li and/or Mg
completely in the metal melt, provided there is an LiCl content of more than 90% in a
KCl–LiCl salt mixture. In this case, the experimental values for the K content in the
metal are even lower than those predicted by the thermochemical calculations
(Figure 4.30). In the course of the treatment of the AlLiMg metal melt with pure
LiCl, a K content of 14 ppm in the metal melt was achieved, with an Li and Mg yield of
over 99.4% in both cases. The reason for the lower experimental K contents in
contrast to the theoretical values is that the solubility of K in solid and liquid
aluminium was not available.