Effects of pouring temperature on the cooling rules of alloy melts and the semi-solid microstructure

A self-developed taper barrel rheomoulding(TBR) machine for preparing light alloy semi-solid slurries was introduced.Relative rotation of the internal and external taper barrel whose surface contains wales and grooves led to an intense shearing turbulence of alloy melts during solidification,and then the semi-solid slurries were prepared.A heat transmission model of TBR process was deduced.Taking A365 aluminum alloy as an experimental material,the related formula between slurry temperature(Tout) and pouring temperature(Tp) of the alloy was obtained.The cooling rules of the alloy melt and the semi-solid microstructure at different pouring temperatures were analyzed.The results show that properly decreasing the pouring temperature of A365 alloy melt can increase the shearing time and shearing frequency for the primary solid phase,thereby obtaining a fine and homogeneous semi-solid microstructure.When the pouring temperature is 640℃,the average grain size of primary particles is 68μm and the shape factor is 0.82.