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The effect of rare earth (RE) elements on the morphologies and sizes of Si phases in the hypereutectic Al-Si alloys modified with P was investigated.The results show that the addition of La element to the hypereutectic Al-Si alloys can enhance the effect of P element on the modification of the primary Si phases.In the multiplex modification of RE-P,the primary Si phase is refiner and the shape of the eutectic Si is changed from long needle-like to short rod-like.Moreover,the agglomeration rate of the primary Si phase is slowed greatly.Even the melt is held for 6 h,the average size of the primary Si phase is still satisfied.The results analyzed by scanning electron microscope (SEM) indicate that La is richer at A1-Si interface than that inα-Al or primary Si phase.The higher the La content in the Al-Si interface,the smaller the primary Si phase.
The effect of rare earth (RE) elements on the morphologies and sizes of Si phases in the hypereutectic Al-Si alloys modified with P was investigated. The results show that the addition of La element to the hypereutectic Al-Si alloys can enhance the effect of P element on the modification of the primary Si phases. in the multiplex modification of RE-P, the primary Si phase is refiner and the shape of the eutectic Si is changed from long needle-like to short rod-like. agglomeration rate of the primary Si phase is slowed greatly. Even the melt is held for 6 h, the average size of the primary Si phase is still satisfied. The results analyzed by scanning electron microscope (SEM) indicate that La is richer at A1- Si interface than that in α-Al or primary Si phase. Higher than La content in the Al-Si interface, the smaller the primary Si phase.