Understand that between the liquidus and solidus lines, a two-component mixture exists as coexisting solid and liquid phases with different compositions than the overall alloy, and that the lever rule sets exactly how much of each phase is present.
Region
Two-Phase (Solid + Liquid)Fraction Liquid
0.333Fraction Solid
0.667Liquidus: T = TA + (TB − TA)·CSolidus: T = TA + (TB − TA)·(C + lens width)Lever rule: fraction liquid = (C0 − C_solidus) / (C_liquidus − C_solidus)Adjust composition and temperature until the point falls between the liquidus and solidus lines — a state where solid and liquid coexist.
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