No abstract

It is known that ultrasonic waves promote nucleation and globulization of solid particles in aluminium alloys. However, the studies performed up to date have been conducted, in the laboratory, using small volumes of aluminium. This article aims to establish the application of ultrasound effect in the A357 aluminium-silicon alloy in amounts of about 2 kg of material. The experiments have been conducted with different parameters of ultrasonic treatment, evaluating the microstructure of the slurry quenched from the semi-solid state. The globulization effect of aluminium α phase by ultrasounds is very effective in the area close to the ultrasonic horn tip and the transmission system, but its effect highly reduces in the regions far away from the source of ultrasonic waves.

The “Rheo-Characterizer” is an apparatus designed to assess the quality control of the semi-solid material. The working principle is based on the recording and subsequent analysis of the force required to transversally cut the semi-solid slurry at constant speed. Semi-solid slurries produced under different conditions while using the SEED process were analyzed with the “Rheo- Characterizer”. The TiB2 grain refiner was also added to evaluate the impact on the microstructure and the cutting force. The microstructural features were measured and the grain size was analyzed for the different processing conditions. The effect of the cutting temperature on the resulting curve was also investigated. The results show that the “Rheo-Characterizer” is capable of differentiating between the varied microstructural morphologies and the solid fraction of the billet.

No abstract