This lecture covers solid-state transformations, focusing on nucleation, solidification, and heterogeneous nucleation. It also discusses nucleation statistics, precipitation sequences, and the kinetics of transformation using the Johnson-Mehl-Avrami-Kolmogrov equation. The presentation delves into nucleation rates, nucleation at grain boundaries, and the derivation of the JMAK equation. Additionally, it explores hardness testing techniques, the correlation between hardness and yield stress, and transformations without diffusion. The lecture concludes with a study of thermodynamics, hysteresis, shape memory effects, and pseudo-elasticity in materials like CuZnSn.