Figure Q1 below shows the equilibrium phase diagram of Lead (Pb)-Tin (Sn) alloy system. (a) (b)...

 

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Figure Q1 below shows the equilibrium phase diagram of Lead (Pb)-Tin (Sn) alloy system. (a) (b) (c) Temperature (°C) (ii) 300 200 100 327°C a+L 18.3 20 183°C 40 *** Liquid 61.9 60 (Pb) Composition (wt% Sn) (Sn) Figure Q1 The equilibrium phase diagram of Lead (Pb)-Tin (Sn) alloy system At a temperature of 200 °C, a melt of 20 wt% Pb-80wt% Sn alloy with a mass of 100 g should have two phases, i.e., solid ß and liquid L phases, respectively. Without changing the temperature of this alloy, please (i) 80 232 C 97.8 100 Suggest how to make this melt become a completely solid phase by changing the composition. Suggest how to make this melt become a completely liquid phase by changing the composition. Suggest one method to strengthen the 20 wt% Pb-80wt% Sn alloy with detailed explanation and justification. Based on the Pb-Sn alloy phase diagram, explain why Pb-Sn alloy was widely used as the solder material in the reflow soldering process in the past and it is much less used in the electronic packaging nowadays. Figure Q1 below shows the equilibrium phase diagram of Lead (Pb)-Tin (Sn) alloy system. (a) (b) (c) Temperature (°C) (ii) 300 200 100 327°C a+L 18.3 20 183°C 40 *** Liquid 61.9 60 (Pb) Composition (wt% Sn) (Sn) Figure Q1 The equilibrium phase diagram of Lead (Pb)-Tin (Sn) alloy system At a temperature of 200 °C, a melt of 20 wt% Pb-80wt% Sn alloy with a mass of 100 g should have two phases, i.e., solid ß and liquid L phases, respectively. Without changing the temperature of this alloy, please (i) 80 232 C 97.8 100 Suggest how to make this melt become a completely solid phase by changing the composition. Suggest how to make this melt become a completely liquid phase by changing the composition. Suggest one method to strengthen the 20 wt% Pb-80wt% Sn alloy with detailed explanation and justification. Based on the Pb-Sn alloy phase diagram, explain why Pb-Sn alloy was widely used as the solder material in the reflow soldering process in the past and it is much less used in the electronic packaging nowadays.

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