Fluidity of a molten alloy during sand casting depends on its solidification range. The phase diagram of a hypothetical binary alloy of components A and B is shown in the figure with its eutectic composition and temperature. All the lines in this phase diagram, including the solidus and liquidus lines, are straight lines. If this binary alloy with 15 weight % of B is poured into a mould at a pouring temperature of 800\,$^\circ$C, then the solidification range is ________________.
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Solidification range = liquidus temperature − solidus temperature at the given alloy composition. Straight-line phase boundaries make interpolation easy.
To find the solidification range, we locate the solidus temperature and liquidus temperature at the alloy composition of 15 wt% B. Since all lines in the diagram are straight, interpolation is direct. The diagram shows that the liquidus at 15 wt% B is approximately 800\,$^\circ$C (the pouring temperature lies exactly on the liquidus line). The solidus temperature for the same composition is about 650\,$^\circ$C, where the alloy becomes fully solid. Therefore, the solidification range is the temperature interval between the start and end of solidification:
\[
\text{Solidification Range} = 800^\circ\text{C} - 650^\circ\text{C} = 150^\circ\text{C}.
\]
Final Answer: 150\,$^\circ$C
