부산대학교 도서관

The Al-TiO2-C refiners were prepared by the in-situ exothermic dispersion method using Al,TiO2 and C powders. The particle sizes of TiO2 were 30,60,90 nm and 200 nm, respectively. The effects of particle size of TiO2 on the refiner microstructure were studied. The refinement effect on industrial pure aluminum was evaluated. The XRD, SEM and EDS techniques were used to characterize the phase composition and the microstructure of Al-TiO2-C refiners. The results show that the Al-TiO2-C refiners compose of Al3Ti,TiC and Al2O3.The particle size of TiO2 directly affects the amount,distribution and morphology of the second phase. When the particle size of TiO2 is 30-90 nm,the amount of Al3Ti and TiC is large. However, the segregation phenomenon is obviously observed. The distribution of particles is not uniform. The Al3Ti is lath-like. When the particle size of TiO2 is 200 nm,the distribution of second phases is uniform and the amount is small. The Al3Ti is blocky. After adding the Al-TiO2-C refiner prepared by 30 nm TiO2, the nucleation temperature of α-Al increases from 659.4 ℃ to 661.8 ℃.Re-heating temperature is dropped from 1.2 ℃ to 0.3 ℃.The minimum average grain size is 633 μm. The refinement effect is the best in this condition.