Jingjie GUO
,
Guizhong LIU
,
Yanqing SU
,
Jun JIA
材料科学技术（英）
A new model was established to calculate the real vapor pressure of Al in the molten Ni-xAl (at. pct) (x=25～50) alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature on the real vapor pressure of Al in the vacuum chamber were analyzed. Because of the impeding effect of the real vapor pressure on the evaporation loss rate, within a short time (less than 10 s), the real vapor pressure tends to a constant value. When the chamber pressure is less than the saturated vapor pressure of Al, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is higher than the saturated vapor pressure, the real vapor pressure of Al approaches to the saturated vapor pressure of Al of the same condition.
关键词:
Real vapor pressure
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null
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null
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null
Hongsheng DING
,
Jun JIA
,
Jingiie GUO
,
Yanqing SU
,
HengZhi FU
,
Jinshan LI
材料科学技术（英）
A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free energy changes have been calculated and discussed.
关键词:
Yuan LIU
,
Jingjie GUO
,
Yanqing SU
,
Hongsheng DING
,
Jun JIA
材料科学技术（英）
Melt spinning rapid solidification technique was employed to fabricate homogeneous Al-In immiscible alloys and their final microstructures and morphologies were investigated. There existed a transition of columnar Al grain®equiaxed grain for the thicker ribbon, butonly columnar Al grain for the thinner ribbon throughout the thickness. In the columnar grain field, most of the fine In particles was distributed within the cells, but a minority of bigger In particles or short rods was perpendicularly distributed at the grain boundaries. In the equiaxed grain field, the fine In particles were located in Al grains and coarser particles were situated at the boundaries. The average particle size increased with increasing distance from the chilled surface throughout the ribbon. At the same wheel speed (same cooling rate), the average particle size increased with raising In content. At the same composition condition, the average particle size decreased with increasing wheel speed and/or decreasing ejection temperature.
关键词:
Al-In immiscible alloy
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,
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Guizhong LIU
,
Jingjie GUO
,
Yanqing SU
,
Jingzhe GUO
,
Jun JIA
,
Hengzhi FU
材料科学技术（英）
In this paper, the critical pressure pcrit and impeding pressure pimpe of the elemental evaporation were defined and studied based on the calculation of the relationship between the evaporation loss rate Nm and the chamber pressure p during melting of NiAl alloys. When the chamber pressure is lower than pcrit or higher than pimpe, Nm tends to be the maximum or minimum value and remains almost unchanged. However, declines sharply with the increase of the chamber pressure when pcrit
关键词:
ISM process
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null
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Wenbin SHENG
,
Jingjie GUO
,
Yanqing SU
,
Hongsheng DING
,
Jun JIA
材料科学技术（英）
A method combining theoretical analysis with experiment is adopted and the flowing process of Ti-48Al-2Cr-2Nb alloy melt poured in a permanent mould during the centrifugal casting process has been analyzed. A mathematical model of the filling process is established and the forming mechanism of internal gaseous defect is summarized. The results of calculation show that the melt fills the mould with varying cross-section area and inclined angle. The filling speed of the cross-section is a function of filling time. The cross-section area is directly proportional to the filling speed and the inclined angle is inversely proportional to the filling speed at a given rotating speed of the platform. Both of them changes more obvious near the mould entrance. The gaseous defect can be formed in several ways and the centrifugal field has an important influence on the formation of the defect. In addition, the filling process in centrifugal field has been verified by wax experiments and the theoretical analysis are consistent with experimental results.
关键词:
Jingjie GUO
,
Yuan LIU
,
Hongsheng DING
,
Yanqing SU
,
Jun JIA
材料科学技术（英）
Using direct finite difference method, a numerical model for simulating the temperature field in the charge during induction skull melting (ISM) has been developed. On the basis of the model, the temperature field in Ti- 47Ni-9Nb ingot has been calculated under various melting conditions. Finally, the processing parameters (melting power, melting-down time and the final melt temperature) have been optimized.
关键词:
