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The table shows the solidification temperatures for various alloys of metal A and metal B - Leaving Cert Engineering - Question (b) - 2016
Question (b)
The table shows the solidification temperatures for various alloys of metal A and metal B. % of metal B in alloy 0 10 20 40 60 70 8... show full transcript
Worked Solution & Example Answer:The table shows the solidification temperatures for various alloys of metal A and metal B - Leaving Cert Engineering - Question (b) - 2016
Step 1
Draw the equilibrium diagram according to the given data.
Answer
To draw the equilibrium diagram, plot the provided solidification temperatures against the percentage of metal B in the alloy.
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Axes:
- X-axis: Percentage of Metal B in Alloy (0% to 100%)
- Y-axis: Temperature (in °C from 175 °C to 350 °C)
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Data Points: Mark the start and end of solidification temperatures according to the table.
- For example, at 0% Metal B, the start is 350 °C and the end is 175 °C, creating a line.
- Repeat this for each percentage of Metal B.
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Lines:
- Connect these points to form the liquidus and solidus lines. The liquidus line shows where the alloy is fully liquid, and the solidus line indicates where it is fully solid.
- Include a 'pasty' region where the alloy starts transitioning from liquid to solid.
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Eutectic Point: Identify the eutectic point where both metals solidify at a specific ratio (at approximately 30% Metal B).
The finished diagram will have curves from the solidus to liquidus, indicating the various phases of the alloy at given temperatures.
Step 2
Label the diagram and describe its main features.
Answer
Label the following key features on the equilibrium diagram:
- Liquid: Indicate that both metals are soluble in each other in the liquid state.
- Liquidus Line: Define the beginning of solidification; above this line, the material is entirely liquid.
- Solidus Line: Define the end of solidification; below this line, the material is entirely solid.
- Pasty Region: Highlight the zone where the alloy transitions from liquid to solid, indicating it is in a mixed phase.
- Eutectic Point: Mark where liquid changes directly to solid without going through a pasty stage.
These features help in understanding how the phases of the metals change with temperature and composition.
Step 3
For the alloy with 30% metal B, determine from the diagram the ratio of the phases at 250 °C.
Answer
At 250 °C, for the alloy with 30% metal B, the equilibrium diagram reveals the following:
- Mass of Solid: From the diagram, it appears that the mass of solid is approximately 30%.
- Mass of Liquid: Correspondingly, the mass of liquid is roughly 23%.
Thus, the ratio of phases can be calculated as:
Mass Ratio = ( \frac{Mass \ of \ solid}{Mass \ of \ liquid} = \frac{30}{23} \approx 1.30 )
This suggests there is 1.30 times more solid than liquid present at 250 °C for the 30% metal B alloy.