  Coherent misfitting precipitates in elastically stressed media such as
$\gamma \prime$ particles in nickel-based super-alloys show various splitting
patterns such as doublets, quartets, or octets due to their misfit strain
energy. While it is an interesting instability phenomenon defying conventional
surface thermodynamics, its mechanism is not completely clear. Through a
phase-field study upon the splitting behavior and morphological evolution of
coherent precipitates, we show that an interface instability driven by elastic
anisotropy and a diffusion field can generate elastically induced splitting
during diffusional phase transition. Particle splitting is triggered by
interface grooving which advances by penetrating grooves into the interior of
the particle. The sequential evolution of shapes during the splitting process
is in good agreement with previous experiments.
