Two regimes of interaction of shock wave and microstructure in heterogeneous medium are studied: (i) equilibrium reversible interscale momentum exchange, (ii) nonequilibrium irreversible momentum exchange. The first regime corresponds to propagation of shock wave in a medium of pre-existing heterogeneity. During the second regime, a dynamic heterogeneity is dominant. Shock tests of D16 Al alloy within impact velocity range of 85÷450 m/s revealed a dependence of above regimes on the strain rate. Maximum dynamic strength is found to be realized at the impact velocity where macroscopic strain rate equals to the local strain rate corresponding to the mesoscale.

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