DSC and X-ray Diffraction Study of a Mixture of Aluminum with 50 wt % of Aluminum Oxide after Plastic Deformation under High Pressure

Al–50 wt % Al2O3 mixtures underwent plastic deformation in an anvil-type high-pressure device at pressures of 0.5–4.0 GPa. The analysis of deformed mixtures was carried out by means of DSC and X-ray diffraction analysis. In deformed mixtures in the range of 200–400°C, a decrease of the mass of samples occurred, which was related to the removal of water adsorbed on the surface of aluminum-oxide particles: an endothermic effect was recorded in this range. Aluminum was oxidized and melted in the range of 500–800°C. These processes were accompanied by exothermic and endothermic processes, respectively. The baric dependences of thermal processes in the range of 30–800°C had a nonmonotonic nature with extremes at 1.0 and 2.5 GPa. According to data of X-ray diffraction analysis, the baric dependence of the sizes of coherent scattering regions was also nonmonotonic and reached extreme values at pressures of 1.0 and 2.5 GPa. Extremes on the baric dependences of parameters describing the properties of deformed mixtures could be related to rearrangements in the electronic structure of aluminum and the aluminum–aluminum-oxide system.