  Two microscopic models, UrQMD and QGSM, were employed to study the formation
of locally equilibrated hot and dense nuclear matter in heavy-ion collisions at
energies from 11.6 AGeV to 160 AGeV. Analysis was performed for the fixed
central cubic cell of volume V = 125 fm**3 and for the expanding cell which
followed the growth of the central area with uniformly distributed energy. To
decide whether or not the equilibrium was reached, results of the microscopic
calculations were compared to that of the statistical thermal model. Both
dynamical models indicate that the state of kinetic, thermal and chemical
equilibrium is nearly approached at any bombarding energy after a certain
relaxation period. The higher the energy, the shorter the relaxation time.
Equation of state has a simple linear dependence P = a(sqrt{s})*e, where a =
c_s**2 is the sound velocity squared. It varies from 0.12 \pm 0.01 at E_{lab} =
11.6 AGeV to 0.145 \pm 0.005 at E_{lab} = 160 AGeV. Change of the slope in
a(sqrt{s}) behavior occurs at E_{lab} = 40 AGeV and can be assigned to the
transition from baryon-rich to meson-dominated matter. The phase diagrams in
the T - mu_B plane show the presence of kinks along the lines of constant
entropy per baryon. These kinks are linked to the inelastic (i.e. chemical)
freeze-out in the system.
