SOLIDIFICATION OF ALLOYS AND MAGMAS yal 
temperature records of the desired mixtures. Because of the undesir- 
able supercooling, Day and Allen, however, recorded the heating, 
rather than the cooling, curve. As will be seen from the diagram, it is 
of the complete solubility type, with no indication of eutectics or inter- 
mediate compounds. It is conclusive evidence that between 100 
per cent. of anorthite and roo per cent. of albite we have an isomor- 
phous series; and microscopic examination was entirely confirmatory. 
IRON-SILICON ALLOYS 
Fig. 6 shows the freezing-point curve of the iron-silicon alloy,’ 
chosen because it represents a rather complex set of conditions. At 
FREEZING POINT CURVE (RON -SILICON ALLOYS 
TEMPERATURE 
W/00 
‘ Oo 79 Zo BO Fo ye) Go go Go 9O .7060 
PERCENT S1L/C0N 
Fic. 6 
A there is evidence of the formation of a compound, the silicide Fe,Si. 
At C (50 atoms per cent. Si) another compound is indicated, of the 
composition FeSi. Up to 333 atoms per cent. of Si, the curve is of 
the type of complete solubility, with resulting solid solutions of iron 
and Fe,Si. Between 334 and 50 per cent., Fe,Si and FeSi are immis- 
1 W. Guertler and G. Tammann, ‘‘Ueber die Verbindungen des Siliciums mit 
dem Eisen,” Zeitsch. f. anorg. Chemie, 1905. 
