b. What temperature would provide the most rapid, isothermal phase transformation of α to γ? What would be the minimum time from onset of the phase transformation to its completion?
Using the isothermal transformation diagram given in Figure 2 for a specific material composition to answer the following (this is NOT an Fe-C steel!). NOTE: Assume that you begin with a single-phase sample of α at 790 C.
a. What temperature on the diagram corresponds to the α-to-γ phase transformation temperature that would be found on an equilibrium phase diagram? Explain your answer.
b. What temperature would provide the most rapid, isothermal phase transformation of α to γ? What would be the minimum time from onset of the phase transformation to its completion?
c. On Figure 2, draw and label a cooling schedule (from 790 C) that will produce a single-phase α material at 100 C. How does the thickness of the piece of material influence your ability to create a single-phase α structure?
d. Why does the time to initiate phase transformation become smaller as the temperature is reduced within the temperature range above the “nose” of the TTT diagram? Be specific, what process is contributing to this delay time? What is the driving force for this phase transformation process in this temperature range?
e. What is the driving force for the phase transformation process within the temperature range below the “nose” of the TTT diagram (CAREFUL!)? Why does the time to initiate the phase transformation increase with a reduction in temperature in this temperature range?
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