The dynamically compressed AlCuZr alloy and technically pure aluminum Al99,5 have been investigated. The jump of microhardness has been found in both materials deformed in the compression test by special hammer. In the cases of AlCu4Zr alloy it appeared at the true strain of about 0,45 and in the case of Al99,5 at the true strain of about 0,3. In both cases the considerably increase of microhardness has been found.
The observation performed by light microscope revealed band microstructure in Al99,5 and AlCu4Zr from the beginning of deformation. With the increase of deformation the density of bands considerably increased. There were not found the substantial differences between the samples before and after the jump of microhardness. However thin foil observations showed the changes of microstructure above the microhardness transient. Above the microhardness jump, the mutually crossing microbands were found in contrast to samples below this point, in which only one family of microbands has observed.