5. Diffusional transformation in solids (10P) a. Write the four different energy terms involved in the calculation of the free energy change in heterogeneous nucleation in solids. (2p) b. List the sequence of various nucleation sites in order of increasing order of AGa (free energy change due to defect destruction). (2p) List the structure and size range of GP Zone, 0" (Theta Double Prime), 0' (Theta Prime) and 0 (Theta) which evolve during the aging process after solution treatment and quenching in Al-4 wt.% Cu alloys. (4p) d. How does partitioning affect the growth of pearlite in Fe-C alloys? (2p) C.