Abstract

This thesis presents an investigation of the effect of the semi-solid processing parameters on aluminium alloy 7075. In particular, this thesis focuses on the effect of the temporal thermal fields. Thermal analysis (TA) was initially performed in order to determine suitable processing conditions and understand the relationship between fraction solid and temperature. A specially designed chamber was used to achieve the cooling rates of 0.13 °C/s and different cooling medium were used to replicate the cooling rates of 0.32 °C/s, 0.36 °C/s and 0.39 °C/s. Different cooling rates had a marginal effect on the liquidus, eutectic and solidus phase change temperatures. The coherency point temperatures were also found to be weakly dependent on the cooling rates within the range investigated within this work. The fraction solid was however found to be strongly dependent on temperature. At temperatures higher than the coherency point (approximately 0.20