“Railway Research Institute” JSC, Moscow, Russia

E. G. Kotova, Post-graduate Student, e-mail: kotova@vniizht.ru
A. E. Mironov, Leading Researcher
I. S. Gershman, Head of Laboratory

The analysis of the microstructure and mechanical properties for experimental alloys of Al – Cu – Zn – Sn – Pb and Al – Si – Cu – Sn – Pb systems has been performed on the samples, which were obtained by casting in cast iron molds. The polythermal layers of Al – Sn – Cu, Al – Pb – Sn, and Al – Si – Sn – Pb – Cu diagrams have been built, analyzed and their phase composition were calculated using the software package “Thermo-Calc”. It was shown that for Al – 7% Sn – Cu-alloys at room temperature Sn and Θ (CuAl₂) are in equilibrium with the solid solution of aluminum, in Al – Pb – Sn-alloys in the temperature range of 230–200 ^оC and 1% Pb and up to 0,06% Sn content (Pb) is in equilibrium with (Al), with increase of the concentration of Sn from 0,06% to 0,17% (Al), (Sn) and (Pb) are in solid-state equilibrium, in the area of the concentration of tin more then 0,17% (Sn) is in equilibrium with (Al), Al – Si – Sn – Pb – Cu-alloys have a region of immiscibility in the liquid state. Metallographic analysis has been investigated with the aids of optical microscopy and scanning electron microscopy. According to the microstructural analysis in Al – Cu – Sn – Pb-alloys CuAl₂, (Sn) and (Pb) are situated along the boundaries of the dendritic cells of the solid solution (Al); the main phase components of the experimental Al – Si – Cu – Sn – Pb-alloys are (Al), (Si), (Sn) and (Pb). The hot-tearing tendency of the experimental alloys has been evaluated by I. I. Novikov method. The tension tests have been realized at the room temperature. The Brinell-hardness and toughness have been determined. The experimental results have been analyzed and referred to the microstructural analysis. Based on this research, the most advanced alloys have been selected for further usage of them like antifriction alloys.

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