Using the isothermal transformation diagram for an iron-carbon alloy of eutectoid composition (Figure 10.22), specify the nature of the final microstructure (in terms of microconstituents present and approximate percentages of each) of a small specimen that has been subjected to the following time-temperature treatments. In each case assume that the specimen begins at 760$$^\circ$$C and that it has been held at this temperature long enough to have achieved a complete and homogeneous austenitic structure.

1. (a) Cool rapidly to 700$$^\circ$$C, hold for 10$$^4$$s, then quench to room temperature.
2. (b) Reheat the specimen in part (a) to 700$$^\circ$$ for 20 h.
3. (c) Rapidly cool to 600$$^\circ$$C, hold for 4 s, rapidly cool to 450$$^\circ$$C, hold for 10 s, then quench to room temperature.
4. (d) Cool rapidly to 400$$^\circ$$C, hold for 2 s, then quench to room temperature.
5. (e) Cool rapidly to 400$$^\circ$$C, hold for 20 s, then quench to room temperature.
6. (f) Cool rapidly to 400$$^\circ$$C, hold for 200 s, then quench to room temperature.
7. (g) Rapidly cool to 575$$^\circ$$C, hold for 20 s, rapidly cool to 350$$^\circ$$C, hold for 100 s, then quench to room temperature.
8. (h) Rapidly cool to 250$$^\circ$$C, hold for 100 s, then quench to room temperature in water. Reheat to 315$$^\circ$$C for 1 h and slowly cool to room temperature.