Gold-iron alloy system

The intermediate phases found in alloys of two true metals have a number of different structures, but many of these are common to more than one system. In addition to the phases already considered in the copper-gold and iron-aluminium systems we shall describe two, one because of its common occurrence and one because of its geometrical interest. 

Alloys suitable for castings that ate to be bonded to porcelain must have expansion coefficients matching those of porcelain as well as soHdus temperatures above that at which the ceramic is fired. These ate composed of gold and palladium and small quantities of other constituents silver, calcium, iron, indium, tin, iridium, rhenium, and rhodium. The readily oxidi2able components increase the bond strength with the porcelain by chemical interaction of the oxidi2ed species with the oxide system of the enamel (see Dental materials). 

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