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The table shows the solidification temperatures for various alloys of Cadmium and Bismuth - Leaving Cert Engineering - Question b - 2019
Question b
The table shows the solidification temperatures for various alloys of Cadmium and Bismuth. % of Cadmium in alloy 0 10 20 30 40 50 60 70 80 90 100 Start of solidific... show full transcript
Worked Solution & Example Answer:The table shows the solidification temperatures for various alloys of Cadmium and Bismuth - Leaving Cert Engineering - Question b - 2019
Step 1
Draw the equilibrium diagram using the given data.
Answer
To draw the equilibrium diagram, plot temperature (°C) on the vertical axis against the percentage of Cadmium in alloy on the horizontal axis. The start of solidification points are:
- (0%, 268°C)
- (10%, 237°C)
- (20%, 205°C)
- (30%, 175°C)
- (40%, 190°C)
- (50%, 235°C)
- (60%, 265°C)
- (70%, 290°C)
- (80%, 310°C)
- (90%, 321°C)
The end of solidification temperature remains at 140°C for all. Connect the start of solidification points with a curve and draw a horizontal line across at 140°C to establish the end of solidification level. Indicate the liquidus line and solidus line. Mark the eutectic point where the temperature lowest and composition show complete transition from liquid to solid state.
Step 2
Label and describe the key features of the diagram.
Answer
Key features to label:
- Liquid phase: Area where both metals (Cadmium and Bismuth) are in liquid form.
- Liquidus line: The curve above which the alloy is liquid; below, it begins to solidify.
- Solidus line: The curve below which the alloy is solid; intermediate area signifies solid and liquid coexistence.
- Eutectic point: Point on the diagram indicating the composition where the two metals completely solidify at the lowest temperature.
Each of these features is crucial in understanding the transition between phases during the solidification of the alloy.
Step 3
Explain the term eutectic alloy.
Answer
A eutectic alloy is defined as a specific mixture of two (or more) metals that are completely soluble in the liquid state but not in the solid state. At the eutectic composition, the alloy solidifies at a lower temperature than any of the individual components, leading to a finely mixed microstructure of the co-existing solid phases.