8. Main causes of imbalance

8.1 Germination, supercooling, hysteresis

The solidification of an alloy takes place through the germination of solid crystals and their subsequent growth. This nucleation can never take place at the equilibrium temperature T _E between liquid and solid, as the appearance of a solid nucleus in the liquid creates a liquid-solid interface with a certain surface energy. This means that supercooling must take place at a temperature below T _E in order to generate sufficient driving force to compensate for the creation of this energy. Indeed, this driving force increases as the supercooling ΔT (ΔT = T _E – T ) increases.

In addition...