Structure of hyper eutectic silumin Al-20Si alloyed with chromium and nickel atoms by compression plasma flow impact

In this work, the structure and phase composition of a hyper eutectic silumin alloy (with a silicon content of 20 at.%) alloyed with nickel and chromium atoms under the action of compression plasma flows are studied. Alloying of the near-surface layer was carried out by preliminary deposition of a corresponding metal coating with a thickness of 1-2 µm followed by exposure to compression plasma flows with a density of absorbed energy providing melting of the near-surface layer. As a result of liquid-phase mixing of the melt, a number of chemical reactions take place leading to the formation of the silicide Ni₂Si and the intermetallic compound Al₃Ni in the case of alloying with nickel, and the complex silicide Al₁₃Cr₄Si₄ when alloying with chromium atoms. Upon subsequent thermal annealing at a temperature of 500℃, Ni₂Si silicide decomposes. (authors)