Q$2(45\%).$ The melting $($fusion$)$ points of pure Germanium and pure Silicon are $940C$ and

$1410oC,$ respectively, and are with fully miscible in both solid and liquid states.

i$.$ Construct the integral free energy curve for the solid solution at $1150C.$ Assume activity is

equal to the mole fraction. At $x_B=0\mathrm{.}5$ determine $(15$ marks$)$:

$G^m$ for the solution; $G_{A(s)\text{a}\text{n}\text{d}}^m{G}_{B(s)}^m\frac{\text{;}}{b}ar\frac{(G{)}_{A(s)\text{a}\text{n}\text{d}}}{b}ar(G{)}_{B(s)}$

ii$.$ Construct the integral free energy curves for liquid and solid solutions at $1000,1150$ and

$1300C.$ Assume activity is given by mole fractions; at each temperature determine the

liquidus and solidus compositions using the tangent method $(15$ marks$).$

iii. Construct the liquidus$-$solidus phase diagram for the system using the explicit equations in

the notes $(15$ marks$).$