(a) For the solidification of nickel, calculate the critical radius r* and the activation...

(a) For the solidification of nickel, calculate the critical radius r* and the activation free energy ΔG* if nucleation is homogeneous. Values for the latent heat of fusion and surface free energy are –2.53 × 109 J/m3 and 0.255 J/m2, respectively. Use the supercooling value found in Table 10.1.

(b) Now, calculate the number of atoms found in a nucleus of critical size. Assume a lattice parameter of 0.360 nm for solid nickel at its melting temperature.

Table 10.1 Degree of Supercooling (ΔT) Values (Homogeneous Nucleation) for Several Metals