ABSTRACT
The liquidus projection for a system is commonly labelled to show the regions of primary solidification. If isotherms are shown on the liquidus projection, they can be used to determine the liquidus temperature for a given alloy. The three-phase reaction commences when the path representing the changing liquid composition during the primary stage intersects a curve on the liquidus projection. Points formed by the intersection of curves on a liquidus projection represent the composition of liquid involved in an invariant reaction. Such a point is formed by the intersection of three liquidus curves, and when the liquid composition reaches it, the invariant reaction occurs. Equilibrium data presented as liquidus projections are often used to study solidification sequences. In order to make the fullest use of such projections, information is also required on the solid state constitution of a given system at the completion of solidification.
