Effect of Si and Cu additions on the phase composition, microstructure and properties of Al-Sn alloys

Abstract

The phase transformations in Al-Cu-Si-Sn alloys were studied using both thermodynamic calculations and experimental methods. The calculated isothermal and vertical sections confirm the presence of fields of liquid phase immiscibility and monotectic reactions. It is shown that annealing at 500 °C, followed by quenching, significantly modifies the morphology of the Sn phase, with the particles acquiring a globular shape due to local melting. The influence of Si and Cu on hardness, density, specific electrical conductivity and manufacturability of the base model alloys, Al-20 wt% Sn and Al-6 wt% Sn, is investigated. It is shown that the Al6Sn4Cu5Si alloy is not inferior to antifriction bronze Cu4Sn4Zn17Pb in terms of tribological characteristics and it significantly exceeds it with regard to density, hardness and thermal conductivity.