Exercises

Interpreting Phase Diagrams: The Binary Isomorphous Phase Diagrams

  • Phases present at some temperature $T$ and overall concentration $C_0$. (Section 10.12.3)
  • The composition of phases using the tie line. (Section 10.12.3)
  • The amount of phases in phase mixtures - or phase fractions, $W$. (Section 10.12.4)
Silver and gold.

Figure 10.12.1 Silver and gold.

Exercise 10.12.1: Silver and Gold
Not Currently Assigned

  1. At $T = 1000 ^{\circ}$C, what phases are present in an alloy that is 20% silver (Ag) and 80% gold (Au) by atomic percent (denoted $x$ (Au) in Figure 10.12.1).

    If liquid phase ($L$) is present, it pure Ag, pure Au, or a liquid solution?

    If a solid phase ($\alpha$) is present, do you have pure Ag, pure Au, or a solid solution?

(Left) The binary isomorphous phase diagram for Cu-Ni and (right) a circle in which to sketch a microstructure.

Figure 10.12.2 (Left) The binary isomorphous phase diagram for Cu-Ni and (right) a circle in which to sketch a microstructure.

Exercise 10.12.2: Binary Isomorphous Phase Diagrams
Not Currently Assigned

After learning about the binary isomorphous Cu-Ni phase diagram, let's practice what we've learned and extend it to the concept of microstructure.

Download the image and sketch a representation of the expected equilibrium microstructure at Point A (green dot) in the circle provided. This microstructure is just a cartoon showing the phases with areas proportional to their phase fractions. Give it a try!

  1. In your file upload, make sure to:

    • Label your phases.
    • Indicate the compositions of each phase (use the tie line to find these).
    • Ensure the phase fractions (weight fractions) are represented accurately in the drawing. calculate the values precisely (use the lever rule to find these).
Pb-Sn system.

Figure 10.12.3 Pb-Sn system.

Exercise 10.12.4: Working with Binary Eutectics
Not Currently Assigned

  1. Consider a 40 wt% Sn 60 wt% Pb alloy at 220 $^{\circ}$ C. Using the phase diagram shown in Figure 10.12.3, find:

    • The phases present at these conditions.
    • The compositions of the phases at these conditions.
    • The phase fraction of the solid phase.

Intermediate Phase Diagrams and Invariant Reactions

A more complex phase diagram.

Figure 10.12.4 A more complex phase diagram.