Abstract: The effects of processing parameters on the morphology， size， amount and distribution of the primary Al3Zr phase during the solidification of AlZr master alloys were investigated by the aluminothermic reduction method in the AlK2ZrF6 reaction system. The results showed that the morphologies of the primary Al3Zr crystals transformed from the small blocky shape to long strip shape， and the size of the primary Al3Zr increased while their amount decreased， with the increase of the molten reaction temperature. When the reaction temperature was below 1000℃， Al3Zr crystals exhibited small blocky shapes; when the temperature was higher than 1000℃， they displayed long strip shapes; when temperature was 1000℃， they displayed the small blocky and long strip mixed morphologies. The sizes of the Al3Zr became larger and the amounts of them became fewer in the refractory mold in comparison to that in the iron mold. With the increase of the K2ZrF6 content， the volume fraction of Al3Zr phase increased gradually， and these crystals grew much finer and with more uniform distribution in the Al matrix.

Key words: AlZr master alloy, AlK2ZrF6 system, primary Al3Zr phase, morphology, process parameter