A 50 wt Ni 50 wt Cu alloy is slowly cooled from 1400 degree

A 50 wt% Ni - 50 wt% Cu alloy is slowly cooled from 1400 degree C to 1200 degree C. At what temperature docs the liquid solidify? What is the composition of this last remaining liquid phase? At what temperature does the first solid phase form? What is the composition of this solid phase?

Solution

1. The first solid phase will form at the temperature at which a vertical line of this composition (50% Ni & 50% Cu) intersects the L–( + L) phase boundary i.e. around 1320°C. (from figure)

2. For Last remaining liquid phase composition, draw horizontal line at temperature 1320°C which is cutting solidus line at a place where Ni is around 62% by wt and Cu is around 38% by wt.

3. First solid phase of the alloy starts at the intersection of this same vertical line (50 wt% Ni & 50 wt% Cu)
with the ( + L)– phase boundary i.e. around 1270°C. (from figure)

4.  For starting composition of solid phase, draw horizontal line at temperature 1270°C which is cutting liquidus line at a place where Ni is around 38% by wt and Cu is around 62% by wt.