Influence of Rare Earth Pr on Microstructure of Al-16%Si Alloy

The modification of rare earth Pr on high wear resistance hypereutectic Al-16%Si alloy was investigated by optical metallurgical microscope,the influence of process parameters on the microstructure was analyzed and the modification mechanism of rare earth Pr was put forward.The results show that the rare earth Pr absorbed on Si phase crystal frontier restrains the presence of large super cooling degree,which boosts the modification of rare earth Pr on silicon phase.With the increase of rare earth Pr content,the size of primary silicon phase is becoming smaller and smaller and the shape of the eutectic Si and α-Al is changed into small circle.With the increase of modifying time,the primary Si becomes small and narrow,but the size of eutectic silicon first decreases and then increases.With the increase of modifying temperature,the modification of rare earth Pr enhances on primary silicon,fades on eutectic silicon.