7) TTT diagrams

a) As a start as to why TTT diagrams are important in the metal fabrication/processing industry, we can look at the following diagrams for the recrystallization of copper at different temperatures. What is a TTT diagram and explain why it is important. Use the figure to support your reasoning

b) What kind of material do we see in the TTT diagram below and what is happening (especially explain the black-gray line and the various round images)

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