2002 年 43 巻 9 号 p. 2285-2291
An experimental study was performed on the homogeneous refinement of microstructures and the improvement of mechanical properties in Al–5 mass%Cu and Al–10 mass%Cu alloys using a novel continuous rheocasting process. The crystal grain size in an Al–10 mass%Cu alloy sheet was 6.9±1.8 \\micron in the continuous rheocasting process, which was much finer than the typical grain sizes on the order of 100 \\micron for the conventional rheocasting process and the grain size of 72±26 \\micron in Al–10 mass%Cu alloy for the batch-type rheocasting by Ichikawa et al. The ultimate tensile strength in the Al–10%Cu alloy sheet was 248 MPa at room temperature, which was higher as compared to the tensile strength of 192 MPa in a die-cast Al–10 mass%Cu alloy. The tensile elongation in the Al–10 mass%Cu alloy sheet was 297% at 773 K, which was resulted from superplasticity. It is considered that the crystal grain size in the Al–10%Cu alloy is determined by the “big-bang” nucleation and the multiplication of crystal grains in the numerous spattered droplets made by a rotating screw-shaped stirrer in the continuous rheocasting process.
