The precipitation behavior of γ′ phase,under various interrupt cooling tests after 1170℃,solution treatment was examined.The results indicate that the size of secondary γ′ precipitates increases with the decrease...The precipitation behavior of γ′ phase,under various interrupt cooling tests after 1170℃,solution treatment was examined.The results indicate that the size of secondary γ′ precipitates increases with the decrease of interrupt temperature,and the shape changes from spherical to butterfly like.The fine tertiary γ′ can form either during the post cool air quenching at high interrupt-temperatures,or during the specified 5℃ min-1cooling.Air quenching at high temperatures cannot suppress further nucleation of tertiary γ′ phase.展开更多
Gas flow field in nozzles and out of nozzles was calculated for Laval orifice and straight orifice nozzles. The results showed that the flow generated by the Laval nozzle had a higher exit velocity in the vicinity of ...Gas flow field in nozzles and out of nozzles was calculated for Laval orifice and straight orifice nozzles. The results showed that the flow generated by the Laval nozzle had a higher exit velocity in the vicinity of the nozzle, in comparison with that of the straight nozzle, that is to say, a Laval nozzle was more efficient than a straight one in disintegrating the melt stream and was apt to produce finer powders. The flow generated by the Laval nozzle was less convergent and the velocity gradient along the radial direction was more moderate than that of a straight nozzle, which could contribute to a broad distribution of melt particles. According to their flow characteristics, the Laval nozzle was reckoned as a better choice of producing larger spray-formed billets.展开更多
基金supported by the Science and Technology Project of Beijing (No. D09080300510901)National High Technology Research and Development Pro-gram of China (No. 2012AA03A514)
文摘The precipitation behavior of γ′ phase,under various interrupt cooling tests after 1170℃,solution treatment was examined.The results indicate that the size of secondary γ′ precipitates increases with the decrease of interrupt temperature,and the shape changes from spherical to butterfly like.The fine tertiary γ′ can form either during the post cool air quenching at high interrupt-temperatures,or during the specified 5℃ min-1cooling.Air quenching at high temperatures cannot suppress further nucleation of tertiary γ′ phase.
基金Item Sponsored by Hi-Tech Research and Development Programof China(2006AA03Z114)National Basic Research Program of China(2006CB605204-2)
文摘Gas flow field in nozzles and out of nozzles was calculated for Laval orifice and straight orifice nozzles. The results showed that the flow generated by the Laval nozzle had a higher exit velocity in the vicinity of the nozzle, in comparison with that of the straight nozzle, that is to say, a Laval nozzle was more efficient than a straight one in disintegrating the melt stream and was apt to produce finer powders. The flow generated by the Laval nozzle was less convergent and the velocity gradient along the radial direction was more moderate than that of a straight nozzle, which could contribute to a broad distribution of melt particles. According to their flow characteristics, the Laval nozzle was reckoned as a better choice of producing larger spray-formed billets.
