Microstructure and Coefficient of Friction of Silumins Obtained by Rapid Solidification

The results of a study of the tribological properties and microstructure of rapidly solidified Al–12.2 wt % Si–0.2 wt % Fe (AK12vp) and Al–12.5 wt % Si–0.8 wt % Mg–0.4 wt % Mn–0.7 wt % Fe–0.9 wt % Ni—1.7 wt %, Cu (Al–Si–M) alloys are presented. The effect of multicomponent alloying on the microstructure of near-eutectic silumin was studied using scanning electron microscopy and X-ray spectrometry. Multicomponent alloying of the Al–Si eutectic alloy with magnesium, manganese, iron, nickel, and copper leads to a reduction in the size of the primary α-Al dendrites to 3–4 μm. Tribological tests carried out under conditions of dry friction with reciprocating motion of the indenter showed that alloying by metals of rapidly solidified eutectic silumin leads to a reduction in the coefficient of friction by 25%. An analysis of the surface state of the track showed that, as a result of deformation heating, the oxidation of the α-Al phase occurs, the destruction of the oxide film, which represents the third body, and its removal beyond the track. The fragmentation of silicon plates in the track area into nano-sized particles was also obtained. The impact of the indenter also leads to a uniform distribution of equiaxed particles of intermetallic compounds while maintaining their phase composition.