= Solution
\Image[/past-exam-of-the-materials-science-course-of-the-university-of-cambridge/2016/paper-1-ag-cu-phase.png]
{title=Original schematic Ag-Cu phase diagram constrained by the supplied endpoints and eutectic tie line; unprovided curve shapes and intermediate temperatures are illustrative}
The horizontal axis is <copper> <mass> percentage. The two <liquidus> branches meet at $(28\%,779^\circ\mathrm C)$ and connect to pure <silver> at $960^\circ\mathrm C$ and pure <copper> at $1083^\circ\mathrm C$. The terminal solid-solution boundaries at the <eutectic temperature> are $9\%$ Cu for $\alpha$ and $92\%$ Cu for $\beta$. Label the single-phase fields $L,\alpha,\beta$, the two liquid-plus-solid fields $L+\alpha,L+\beta$, and the lower two-solid field $\alpha+\beta$.
The <solidus> boundaries link the pure-component melting points to their terminal solubility limits; the eutectic isotherm spans the three-phase tie line. Below it, the <solvus> branches approach pure Ag and pure Cu at room <temperature>. The supplied data determine this topology and the marked points, \b[not the exact shapes of every boundary]. The drawing therefore does not invent a numerical <liquidus> <temperature> for an intermediate composition.
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