Phase diagrams

1.) Sketch the eutectic and the peritectic phase diagrams and label all phase regions. [6 Marks]
2.) Sn and Bi are important alloying elements for lead-free solders. The Sn-Bi phase diagram is
shown below.
a. Construct the schematic cooling curves between 25 °C and 300 °C for the alloys c1 to c3,
indicate transition temperatures, phases present and phase reactions. [6 Marks]
i. c1: c(Bi)=5.0 at%
ii. c2: c(Bi)=20.0 at%
iii. c3: c(Bi)=43.0 at%
b. Sketch and annotate the microstructures of the alloy c2 at temperatures 160°C and
100°C. [4 Marks]
c. Determine the relevant phase compositions and phase-fractions of alloy c2 at 160 °C. [4

Sample Solution