In a simple class of ternary alloys the solid phases are the three component metals, each holding in solution a relatively small proportion of the other two. Any one of the three phases may be present as a separate constituent, any two may be associated together as a binary eutectic, and the three together form a ternary eutectic. The structural constituents of such a ternary alloy are—

(1) Primary crystals of one phase,

(2) Binary eutectic of two phases,

(3) Ternary eutectic of three phases.