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The table shows the solidification temperatures for various alloys of Cadmium and Bismuth - Leaving Cert Engineering - Question b - 2012
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 8... 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 - 2012
Step 1
Using the graph paper supplied, draw the thermal equilibrium diagram according to the given data;
Answer
To draw the thermal equilibrium diagram, follow these steps:
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Set Up Axes: Create a horizontal axis for the percentage of Cadmium in the alloy (0% to 100%) and a vertical axis for temperature (ranging from approximately 0°C to 350°C).
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Plot Points: Using the given data, plot the start and end of solidification temperatures for different Cadmium percentages:
- For 0% Cadmium, plot (0, 268) for start and (0, 140) for end.
- Continue plotting each percentage incrementally as provided in the table until 100% Cadmium.
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Draw Lines: Connect the points according to the state of the alloy:
- Draw a liquidus line connecting the start points.
- Draw a solidus line connecting the end points.
- Mark the eutectic point.
- Indicate regions (liquid, solid, and liquid + solid) accordingly.
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Final Touches: Label all lines, points, and the phases distinctly on the diagram.
Step 2
Label and describe the main features of the diagram;
Answer
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Liquidus Line: This line indicates the temperatures at which the alloy is completely liquid. Above this line, the mixture is fully liquid.
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Solidus Line: This line represents the temperatures at which the alloy is completely solid. Below this line, the mixture is entirely solid.
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Eutectic Point: The point where both Cadmium and Bismuth solidify simultaneously from a liquid state without passing through a pasty state.
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Regions Indicated:
- Liquid Region: Above the liquidus line where both metals are fully solubilized.
- Solid Region: Below the solidus line where both metals are solid.
- Liquid + Solid Region: Between the liquidus and solidus lines, where both liquid and solid phases coexist.
Step 3
Explain the term eutectic alloy;
Answer
A eutectic alloy is a specific mixture of metals that melts and solidifies at a lower temperature than its individual components. In solid phase, the alloys remain completely solid while they are in the liquid phase. For example, Cadmium and Bismuth form a eutectic alloy that solidifies at a certain composition, combining desirable characteristics from both metals.