The modification effect of CX-type (CX means the modifiers that have longeffective term) modifiers applied in ZL108 and ZL104 Al-Si alloys has been studied in detail. Theresults show that the morphologies of the eutec...The modification effect of CX-type (CX means the modifiers that have longeffective term) modifiers applied in ZL108 and ZL104 Al-Si alloys has been studied in detail. Theresults show that the morphologies of the eutectic silicon and the primary silicon can be modifiedand refined simultaneously. The modification effect acts quickly and can maintain a period of 8 h bythe CX-type modifiers. The CX-type modifiers increase the mechanical properties of Al-Si alloys andimprove the service properties of machine parts made of Al-Si alloys (such as piston and cylinderetc.). In modifying processes, the amount of the addition of CX-type modifiers is smaller than thatof any other modifiers, and the modifying procedures are simple. There are no smoke, no dust, and noirritant smell in modifying processes using CX-type modifiers. Therefore, the CX-type modifiershave advantages in economy and environment protection.展开更多
A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series f...A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series form. It theoretically confirms the mechanism of melt nucleating: as long as the convection with transverse directions exists, the melt temperature on the front of the solid-liquid interface would be not only periodical along the direction which is perpendicular to the direction of crystal growth, but also oscillatory and exponential decay along the direction of crystal growth; this oscillatory property, i.e. temperature fluctuation, leads to local supercooling, accelerates local temperature fluctuation and then results in a large number of nuclei.展开更多
基金This work was supported by National Natural Science Foundation of China (No.59771011).
文摘The modification effect of CX-type (CX means the modifiers that have longeffective term) modifiers applied in ZL108 and ZL104 Al-Si alloys has been studied in detail. Theresults show that the morphologies of the eutectic silicon and the primary silicon can be modifiedand refined simultaneously. The modification effect acts quickly and can maintain a period of 8 h bythe CX-type modifiers. The CX-type modifiers increase the mechanical properties of Al-Si alloys andimprove the service properties of machine parts made of Al-Si alloys (such as piston and cylinderetc.). In modifying processes, the amount of the addition of CX-type modifiers is smaller than thatof any other modifiers, and the modifying procedures are simple. There are no smoke, no dust, and noirritant smell in modifying processes using CX-type modifiers. Therefore, the CX-type modifiershave advantages in economy and environment protection.
基金This work was financially supported by the Major State Basic Research Development Program of China (No. G2000067206_1).
文摘A three-dimensional steady model of temperature fluctuation with melt convection is studied. It is proved that there exists a unique and stable solution in the model and the solution is expressed in a Fourier series form. It theoretically confirms the mechanism of melt nucleating: as long as the convection with transverse directions exists, the melt temperature on the front of the solid-liquid interface would be not only periodical along the direction which is perpendicular to the direction of crystal growth, but also oscillatory and exponential decay along the direction of crystal growth; this oscillatory property, i.e. temperature fluctuation, leads to local supercooling, accelerates local temperature fluctuation and then results in a large number of nuclei.
