  We propose a hybrid model governed by the Blume-Emery-Griffiths (BEG)
Hamiltonian with a mean-field-like interaction, where the spins are randomly
quenched such that some of them are "pure" Ising and the others admit the BEG
set of states. It is found, by varying the concentration of the Ising spins,
that the model displays different phase portraits in concentration-temperature
parameter space, within the canonical and the microcanonical ensembles.
Phenomenological indications that these portraits are rich and rather unusual
are provided.
