6. The average grain diameter for a nickel alloy was measured as a function of time at 650 C and the data is tabulated below. Answer the following questions assuming the grain size follows the ideal grain growth law given by: d2 - dj = Kt time (min) Grain diameter (mm) 30 3.9 x 10 90 6.6 x 10 a. What was the original grain diameter? b. What grain diameter would you predict after 150 min at 650 C? c. Assuming the constant K exhibits an Arrhenius temperature dependence, explain how the temperature is captured in the ideal grain growth law, d. What additional experimental data is needed to determine the activation energy for grain growth