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The table shows the solidification temperatures for various alloys of metal A and metal B - Leaving Cert Engineering - Question (b) - 2013
Question (b)
The table shows the solidification temperatures for various alloys of metal A and metal B. % of metal B in alloy 0 20 40 60 80 100 Start of solidification (°C) 27... 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) - 2013
Step 1
Using the graph paper supplied, draw the thermal equilibrium diagram according to the given data.
Answer
Below the liquidus line, the alloy is in a liquid state, transitioning into a pasty state between the liquidus and solidus lines. Below the solidus line, it is completely solid.
- Liquid: Represents alloys soluble in each other in liquid form.
- Pasty: This phase is where solid and liquid coexist as cooling occurs.
- Solid: Alloy completely solidified. Label these areas accordingly.
Step 2
Determine the composition of the phases present at 450 °C for the alloy containing 60% of metal B.
Answer
At 450 °C, based on the thermal equilibrium diagram, we can identify the composition by drawing a horizontal line at this temperature.
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Intersection Points: At the intersection of the 450 °C line with the liquidus and solidus lines, determine the relevant percentages of metal A and B.
- For 60% metal B, we find that the composition at this point indicates:
- X: Liquid phase contains 30% A and 70% B
- Y: Solid phase contains 80% B and 20% A.
- For 60% metal B, we find that the composition at this point indicates:
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Conclusion: Thus, at 450 °C, the alloy containing 60% of metal B consists of:
- Liquid Phase: 30% A and 70% B.
- Solid Phase: 80% B and 20% A.