Bianchi type I universe models with irreversible matter creation

The effects of matter creation on the evolution and dynamics of an anisotropic Bianchi type I space-time is investigated in the framework of open thermodynamic systems theory. For a cosmological fluid obeying a Zel'dovich type equation of state (rho = p) and with particle creation rate proportional to the square of the mean Hubble function and to the energy density of matter, respectively, the general solution of the gravitational field equations can be expressed in an exact parametric form. Generically all models start from a non-singular state. In the large time limit anisotropic cosmological models with particle creation rate proportional to the square of the Hubble function end in an isotropic hat (inflationary or non-inflationary) phase while models with particle source function proportional to the energy density of matter do not isotropize, ending in a Kasner-type geometry.