Because a pure metal has a clearly

Because a pure metal has a clearly defined melting (or freezing) point, it solidifies at
a constant temperature, as shown in Fig. 10.1. Pure aluminum, for example, solidifies
at 660°C, iron at 1537°C, and tungsten at 3410°C. (See also Table 3.1 and Fig.
4.4.) After the temperature of the molten metal drops to its freezing point, its temperature
remains constant while the latent heat of fusion is given off. The
solidi/Qcation front (solid-liquid interface) moves through the molten metal from the
mold walls in toward the center. The solidified metal, called the casting, is taken out
of the mold and allowed to cool to ambient temperature.