(Solved): Part II: Using the phase diagram and considering an alloy of composition \( 80 \mathrm{wt} \% \) Sn ...

Part II: Using the phase diagram and considering an alloy of composition \( 80 \mathrm{wt} \% \) Sn- 20 wt \( \% \mathrm{~Pb} \) which starts initially in liquid phase and solidifies by cooling slowly from \( 300^{\circ} \mathrm{C} \) down to \( 180^{\circ} \mathrm{C} \). 1) At approximate what temperature does the first solid phase form? 2) At what temperature does complete solidification of the alloy occurs? b) Part III: Using the phase diagram and considering the alloy of composition 80 wt \( \% \) Sn- 20 wt \( \% \mathrm{~Pb} \) which is held at \( 180^{\circ} \mathrm{C} \) answer the following questions: 1) What are the phases present in the given alloy at this temperature? 2) What are the concentrations \( \mathrm{C} \alpha \) and \( \mathrm{C} \beta \) of \( \mathrm{Sn} \) in the \( \alpha \) and \( \beta \) phases at this temperature? 3) Determine the mass fractions \( W_{\alpha} \) and \( W_{\beta} \) of the \( \alpha \) and \( \beta \) phases present in the alloy at this temperature?