In analogy to Fig. 2 the solidification paths of these two
Al–Sn–Cu alloy samples are projected onto the partial liquidus
surface up to 25 at.% Cu in Fig. 7a and b, where the
thin lines show the calculated lines of double saturation.
The composition of sample #1 is marked by a circle in
Fig. 7a. Starting from this homogeneous liquid L0 the primary
liquid demixing begins at 667 C with formation of
L00 with very similar composition, indicated by the short
dotted tie line. This primary path L0 + L00, indicated by
the curves ‘‘1”, ends at 530 C where the crystallization
of (Al) starts along the short curves ‘‘2” representing
L0 + L00 + (Al), and ending in the point ‘‘3”, the invariant
ternary monotectic reaction L0 ? L00 + (Al) + HAl2Cu at
524 C.