The Al-5Ti-0.5B-0.5C grain refiner was pre-pared by powder metallurgy(PM).Microstructures of the grain refiner and its grain refinement performance in commercially pure aluminum(Al)were investigated by X-ray diffracti...The Al-5Ti-0.5B-0.5C grain refiner was pre-pared by powder metallurgy(PM).Microstructures of the grain refiner and its grain refinement performance in commercially pure aluminum(Al)were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),and differential scanning calorimetry(DSC).It is found that the average grain size of commercially pure Al can be reduced from~15,000 to~180μm by the addition of Al-5Ti-0.5B-0.5C grain refiner prepared by PM,based on 0.01 wt%Ti addition.The grain refinement efficiency begins to decrease slightly when the grain refiner is kept in the melt for 60 min.The grain refinement is attributed to high stability,proper size,and high density of Al3Ti,TiB2,and TiC particles.展开更多
Primary solidification phase and lamellar orientation are investigated in Ti-45Al-7Nb alloy at very high ratio of temperature gradient to growth rate （G/v） by a liquid-metal-cooled directionally solidified method. I...Primary solidification phase and lamellar orientation are investigated in Ti-45Al-7Nb alloy at very high ratio of temperature gradient to growth rate （G/v） by a liquid-metal-cooled directionally solidified method. It shows that Ti-45Al-7Nb alloy solidifies with primary ct phase. Longitudinal （parallel to growth direction） microstructure shows that a dendrites in solid-liquid mushy zone are discontinuous and transverse mierostructure of a dendrites is worm-like feature. Growth direction of a phase is about 80° away from （0001）,a direction, and close to （1120） a direction. The corresponding lamellar orientation is aligned at the angle of about 10° to growth direction, which is consistent with a-dendrite growth direction according to Blackburn orientation relationship. Therefore, due to the altered growth direction of a phase, the lamellar orientation in Ti-45Al-7Nb alloy is controlled at the G/v ratio of 5 × 10^9 K.sm^-2.展开更多
基金financially supported by the National Basic Research Program of China (No. 2012CB619503)the National High Technology Research and Development Program of China (No. 2013AA031001)the International Science & Technology Cooperation Program of China (No. 2012DFA50630)
文摘The Al-5Ti-0.5B-0.5C grain refiner was pre-pared by powder metallurgy(PM).Microstructures of the grain refiner and its grain refinement performance in commercially pure aluminum(Al)were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM),and differential scanning calorimetry(DSC).It is found that the average grain size of commercially pure Al can be reduced from~15,000 to~180μm by the addition of Al-5Ti-0.5B-0.5C grain refiner prepared by PM,based on 0.01 wt%Ti addition.The grain refinement efficiency begins to decrease slightly when the grain refiner is kept in the melt for 60 min.The grain refinement is attributed to high stability,proper size,and high density of Al3Ti,TiB2,and TiC particles.
文摘Primary solidification phase and lamellar orientation are investigated in Ti-45Al-7Nb alloy at very high ratio of temperature gradient to growth rate （G/v） by a liquid-metal-cooled directionally solidified method. It shows that Ti-45Al-7Nb alloy solidifies with primary ct phase. Longitudinal （parallel to growth direction） microstructure shows that a dendrites in solid-liquid mushy zone are discontinuous and transverse mierostructure of a dendrites is worm-like feature. Growth direction of a phase is about 80° away from （0001）,a direction, and close to （1120） a direction. The corresponding lamellar orientation is aligned at the angle of about 10° to growth direction, which is consistent with a-dendrite growth direction according to Blackburn orientation relationship. Therefore, due to the altered growth direction of a phase, the lamellar orientation in Ti-45Al-7Nb alloy is controlled at the G/v ratio of 5 × 10^9 K.sm^-2.
