Equilibrium cooling of PbSn alloys with three different comp

Equilibrium cooling of Pb-Sn alloys with three different compositions ends at points A, B and C as shown in the phase diagram below. The three micrographs on the right show the corresponding microstructures. Please select the correct points for the micrographs.

Solution

The Lowest photograph of the microstructure is for Point C

It is the microstructure for eutectic Pb - Sn microstructure

The top photopgraph is for microstructure at Point B

It is the microstructure for hypoeutectic Pb - Sn microstructure

The middle photopgraph is for microstructure at Point A

Therefore the Order from top to bottom is   B , A & C