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(a) For the solidification of iron, calculate the critical radius r and the activation free energy G if nucleation is homogeneous. Values for the latent heat of fusion and surface free energy are 1.85109J/m3 and 0.204J/m2, respectively. Use the supercooling value T= 284K, and the melting point of iron is 1538C. Critical Radius, r= nm Activation Free Energy G= J (b) Now calculate the number of atoms found in a nucleus of critical size. Assume a lattice parameter of 0.292nm for solid iron at its melting temperature. Number of Atoms for Critical Size = atoms/critical nucleus