Change in the morphology of dendrite primary crystals heated at a temperature of solidification range was examined in hypoeutectic Al–Si–Cu alloys. Dendritic α–Al crystals, which have been refined by the addition of grain refiner, Ti–B and cast into copper mold with the cooling rate more than 10 K/s, are easily spheroidized only by heating to semi-solid state. The size of spheroidized α–Al phases is about 100 μm in diameter under the semi-solid state of fraction solid 0.4 at 860 K. This morphology of α–Al crystals is suitable for the semi-solid squeeze casting. Semi-solid squeeze cast Al–7% Si–3%Cu alloys containing 0.1~1.0%Fe have superior in tensile properties, especially in elongation. The elongation of an as-cast alloy containing 1%Fe is 9%. The tensile properties of semi-solid squeeze cast alloys are further improved by solution heat treatment.
