PHYSICOCHEMICAL TRANSFORMATIONS OF ALUMINUM AND QUARTZ POWDERS MIXTURE UNDER LOADING BY SPHERICAL CONVERGING SHOCK WAVES

The phase composition and structure of a mixture of aluminum and quartz powders taken in a ratio of 1:1 have been studied after loading by spherical converging shock waves. A number of concentric layers (zones) have been observed in the sample after shock-wave loading. The presence of several zones in the sample reflects the specific features of the processes occurring in different pressure ranges. It has been established that pressures below ~45 GPa cause only additional compacting of the material and deformation of aluminum and quartz. In this case, the quartz grain size substantially decreases up to the transition into the X-ray amorphous state. The attainment of a pressure of ~45 GPa initiates the solid-state reaction of SiO 2 decomposition, which leads to the precipitation of pure silicon and the evolution of oxygen. The beginning of the silicon precipitation and the chemical reaction of Al 2 O 3 formation are separated over the pressure scale. The critical pressure, which is necessary for the solid-state chemical reaction of the Al 2 O 3 formation, is about 50 GPa.