1. EXPERIMENT # 9 Instructor: M.Yaqub
Pb – Sn PHASE DIAGRAM
EXPERIMENT # 9
Instructor: M.Yaqub

2. SOLUTION
Solid solution: Consists of atoms of at least two different types
Solute  an element or compound present in a minor concentration
Solvent  an element or compound in greater amount; host atoms.
Solubility Limit: The maximum concentration of a solute atoms that may dissolve in the solvent to form a solid solution at some specific temperature.

3. PHASE
Phase: defined as a homogeneous portion of a system that has uniform physical and chemical characteristics.
Every pure material is considered to be a phase
Also every solid, liquid, and gaseous solution
e.g., syrup solution is one phase, and solid sugar is another

4. PHASE DIAGRAM Equilibrium Phase diagram:
Represents the relationships between temperature and the compositions and the quantities of phases at equilibrium.
Also known as phase, equilibrium or constitutional diagram
A binary alloy is one that contains two components.

5. Pb – Sn PHASE DIAGRAM
a - Solid solution of tin in lead (tin “Sn” is solute and lead “Pb” is solvent)
Solubility limit is 18.3% at 183 oC
b - Solid solution of lead in tin (lead “Pb” is solute and tin “Sn” is solvent)
Solubility limit is 2.2% at 183 oC
Eutectic point at 61.9% Sn at 183 oC

6. Pb – Sn PHASE DIAGRAM

7. DIFFERENTIAL SCANNING CALORIMETR
Differential Scanning Calorimeter (DSC) is used to make a phase diagram.
Read the hand out for detail procedure.

8. PLOT OF HEAT FLOW

9. LAB REPORT
From the resultant DSC curves determine the following parameters:
Initial melting temperature for each sample.
Melting peak for each sample.
Final melting point for each sample.
Calculate the heat of fusion, which is the area under the curve between the solid and the dotted lines for each sample.

10. LAB REPORT (Continue)
Plot the measured transition temperatures on the Pb-Sn phase diagram.
Tabulate all values for all tested specimens in a table format.
Estimate the mass fractions of each phase in the microstructure given below.
Predict the equilibrium mass fractions of each phase using the phase diagram and the lever rule.