抄録
Al-Si binary alloys of various Si compositions were stirred with a rotor at 0.83∼12.5 s−1 during continuous cooling from the liquid to the partially solidified state, and the slurry in which primary crystals were suspended was obtained. Relations between the apparent viscosity obtained as a value of torque and the structure of the slurry were studied. Results obtained are as follows.
(1) Primary α crystals became finer under stirring with increasing Si composition and with increasing revolution speed of the rotor in the hypo-eutectic alloys such as Al-2, 5, and 8%Si alloys.
(2) Eutectics became massive in the Al-12.5%Si eutectic alloys and grew somewhat coarser as the eutectic reaction progressed, and the torque value increased with progress of the eutectic reaction.
(3) Eutectics enriched in α phase crystallized spherically so as to surround the primary Si crystal with progress of the eutectic reaction and with increasing revolution speed in the hyper-eutectic alloys such as Al-17%Si alloys.
(4) The torque value was not increased with increasing volume fraction of the primary Si crystals and was markedly increased with growth of the massive eutectics containing the primary Si crystals in the Al-17%Si alloys.
