Synthesis of surface layers hardened by metal trialuminide compound in al–si alloy under compression plasma flows impact

The structure, phase, and element composition of Al–12%Si piston silumin surface layer alloyed with titanium, zirconium, or niobium atoms were investigated in this work. Alloying was carried out by deposition of an alloying element coating on the silumin surface and subsequent treatment with compression plasma flows generated by a gas-discharge magnetoplasma accelerator. The findings showed that plasma impact resulted in the formation of a composite surface layer containing a supersaturated aluminum solid solution and disperse intermetallic phases on the basis of Al₃Ti, Al₃Zr, and Al₃Nb compounds with a tetragonal D0₂₂ crystal lattice. The size of intermetallic particles was in the range of 1–4 µm. Silicon atoms took part in the formation of a supersaturated Al(Si) solid solution and intermetallic phases, e.g., (Al, Si)₃Zr. The synthesized composite layer possessed a high hardness value (up to 4.4 GPa). The main mechanisms of the structure transformation during plasma impact were discussed.