Since the crystallographic orientation of a cellular colony derives from the grain it grows away from, experimental interest in discontinuous precipitation (DP) has centred on how nucleation and growth rates are affected by the misorientation of the initiating grain boundary. There has been little attention paid to the nature of the interface at the reaction front. Ageing experiments on Ag-7.5Cu at 2500C showed there to be two DP colony populations with distinctly different growth behaviours. EBSD studies have shown that as the colonies grow there is a build-up of misorientation behind the reaction front and eventually the fast growing colonies are surrounded by interfaces close to particular low Σ coincident site lattice (CSL) misorientations with respect to the grain into which they are growing. On the other hand, slow growing colonies are characterised by misorientations close to a different set of low ΣCSLs. The growth mechanisms behind this behaviour will be discussed
