Grain refinement of primary silicon in hypereutectic Al-Si alloys by different P-containing compounds

The grain refinement behavior of Si-3 P,Si-25 Mn-10 P,and Al-10 Si-2 Fe-3 P master alloys on hypereutectic Al-24 Si alloy was studied.Microstructure analysis indicates that the P-containing compounds in the three master alloys are Si P,Mn P,and Al P,respectively.The coarse flower-like primary silicon in the Al-24 Si alloy transforms into smaller,well-distributed blocks with the addition of various master alloys.When pouring at 840°C,the average grain size of the primary silicon refined by Si-25 Mn-10 P master alloy with a holding time of 30 min is about 18μm,which is significantly smaller than those refined by Si-3 P and Al-10 Si-2 Fe-3 P master alloys.The grain size shows an increasing trend when the holding time is further prolonged.Higher holding temperature has a positive effect on the grain refinement of Si-25 Mn-10 P master alloy.The grain refinement mechanism of the three master alloys was also discussed.

Migration behavior and aggregation mechanism of SiC particles in silicon melt during directional solidification process

SiC inclusions in a multicrystalline silicon ingot have a negative effect on the performance of solar cells.The migration behavior and aggregation mechanism of SiC particles in the silicon melt during the directional solidification process was studied.Results show that SiC particles collide and aggregate in the melt due to the effect of melt flow.Larger aggregation of SiC particles is easily deposited at the bottom of the melt,whereas smaller SiC particles are pushed to the top of melt.Meanwhile,the particles migrate to the edge of melt under the effect of electromagnetic force.Furthermore,the enrichment region of SiC particles can be controlled by adjusting the temperature field distribution of the melt.With an increase of the melt temperature,the SiC particles are enriched at the top of the silicon ingot,indicating that SiC particles can be effectively separated from silicon.