Features of damage and modification of surface layers of Al and its alloys by powerful energy flows in a plasma focus device

The results of the analysis of damageability and modification of the structural-phase state of the surface layers of aluminum and its alloys by powerful flows of fast high-energy ions and high-temperature plasma in Plasma focus devices, as well as using pulsed laser radiation. Pure Al, an alloy of the Al – Mg – Li system, a duralumin alloy, and a composition of a ceramic coating Al2O3 on an Al substrate are considered. It is shown that in the regime of Al irradiation with a power density of q ≈ 106 – 107 W/cm2 in the nano- and microsecond range of pulse durations, ultrafast crystallization of melted surface layer occurs with the formation of a wavy surface relief and the structural fragments of sub-microcrystalline and nanoscale size. After the action of deuterium plasma flows on a duralumin alloy tube located along the axis of the Plasma focus device a modification of the structural-phase state of the alloy is observed: the initial two-phase state of an αAl-solid solution of copper in aluminum and inclusions of the second phase of CuAl2 became fine-grained and single-phase due to the dissolution of CuAl2 particles in the melt. Irradiation of an alloy of the Al – Mg – Li system containing (wt %) 2 % Li and 5 % Mg at q = 5·106 W/cm2, t = 50 – 100 ns after four pulsed impacts of fast ions and deuterium plasma led to the modification the structural-phase state of the surface layer of the alloy, associated with an increase in the content of magnesium oxide and a decrease in the crystal lattice parameter of the Al-based solid solution. The formation of spherical cavities due to the evaporation of lithium into the internal micropores of the surface layer was also found. The low damage and structural stability of Al2O3 ceramics on an Al substrate under beam-plasma impacts in plasma focus device with a radiation power density q ≤ 108 – 109 W/cm2 in the nano- and microsecond range of pulse duration is noted. At the same time, the Al2O3/Al composition was unstable to pulsed laser radiation in the free-running mode (q = 105 – 106 W/cm2, t = 0.7 ms) and Q-switch mode (q = 107 – 108 W/cm2, t = 80 ns). In both cases the coating peeled off from the substrate.