The work presented in this thesis aims to provide in-situ experimental observations, obtained with neutron and synchrotron techniques, on the decomposition of austenite into ferrite and pearlite in carbon steel and to relate these observations to physical models that describe the phase transformation kinetics as grain nucleation and growth processes. This thesis describes unique neutron and synchrotron experiments that give in-situ information on the dynamic behavior of grains inside carbon steel during solid-state phase transformations, even down to the level of individual grains.
