Features of the Plastic Flow of Sintered Al–12Si–xSn Alloys

Resumo

The feasibility of obtaining a self-lubricating composite material of the Al–Sn system with the alloyed matrix by the liquid-phase sintering of compacts obtained from the mixture of powders of the eutectic Al–12Si alloy and tin powders was investigated. The porosity of the raw compacts was ~10%; the strength of the sintered Al–12Si–xSn composites was significantly lower as compared with the additive value. The porosity of compacts decreased and the strength reached the theoretical value after additional hot densification of the sintered samples at 200 and 250°C (lower and higher than the tin melting point). The plasticity of composites under compression after densification increased as well and showed its maximum in the composite with 10–20% Sn. Analysis of the compression curves showed that, for the sintered composites, the long linear stage of plastic flow with a low coefficient of strain hardening is a characteristic feature. With the increase in the tin content, the stage of the linear flow shortens and with the 40% Sn concentration disappears. The transcrystalline localized flow and material cracking is observed before fracture.