  X-ray imaging observatories have revealed hydrodynamic structures with linear
scales ~ 10 kpc in clusters of galaxies, such as shock waves in the 1E0657-56
and A520 galaxy clusters and the hot plasma bubble in the MKW 3s cluster. The
future X-ray observatory IXO will resolve for the first time the metal
distribution in galaxy clusters at the these scales. Heating of plasmas by
shocks and AGN activities can result in non-equilibrium ionization states of
metal ions. We study the effect of the non-equilibrium ionization at linear
scales <50 kpc in galaxy clusters. A condition for non-equilibrium ionization
is derived by comparing the ionization time-scale with the age of hydrodynamic
structures. Modeling of non-equilibrium ionization when the plasma temperature
suddenly change is performed. An analysis of relaxation processes of the FeXXV
and FeXXVI ions by means of eigenvectors of the transition matrix is given. We
conclude that the non-equilibrium ionization of iron can occur in galaxy
clusters if the baryonic overdensity delta is smaller than 11.0/tau, where
tau<<1 is the ratio of the hydrodynamic structure age to the Hubble time. Our
modeling indicates that the emissivity in the helium-like emission lines of
iron increases as a result of deviation from the ionization equilibrium. A slow
process of helium-like ionic fraction relaxation was analyzed. A new way to
determine a shock velocity is proposed.
