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

摘要

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 densifica-tion 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.