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 ch...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<P<Pimpe. A method has been put forward to calculate the pcrit and pimpe of Al evaporation in a Ni-XAI (x=25-50 at. pct) melt. The calculation result shows that the pcrit or pimpe is a second-order function of the molar percentage of Al and the melting temperature.展开更多
A new model was established to calculate the real vapor pressure of Al in the molten Ni-xAl （at.pct） （x=25;0） alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature o...A new model was established to calculate the real vapor pressure of Al in the molten Ni-xAl （at.pct） （x=25;0） 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.展开更多
Based on the program developed to simulate the temperature field for ISM(Induction Skull Melting) process, the effects of power increasing rate and charge mass on the melting throughout time and the energy (consumptio...Based on the program developed to simulate the temperature field for ISM(Induction Skull Melting) process, the effects of power increasing rate and charge mass on the melting throughout time and the energy (consumption) for TiAl alloys were studied. The results show that the melting throughout time decreases (exponentially) with the increasing of the power increasing rate and it linearly increases with the increasing of the charge mass. There is a critical power increasing rate for different charge masses. At this critical power increasing rate, the charge can be molten when the melting power just reaches 300 kW. There exists an optimal power increasing rate, i.e. 1.3 kW/s. At the optimal power increasing rate, the energy consumption for melting the charge is the minimum. The charge mass has noticeable influence on the energy consumed by unit mass and the ratio of effective energy.展开更多
A new model was established to calculate the real vapor pressure of the Al element in the molten Ti x Al ( x = 25 ～ 50, mole fraction, %) alloy. The effects of the holding time, chamber pressure, mole fraction of Al ...A new model was established to calculate the real vapor pressure of the Al element in the molten Ti x Al ( x = 25 ～ 50, mole fraction, %) alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature on the real vapor pressure of Al element 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 the Al component, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is larger than the saturated vapor pressure, the real vapor pressure is equal to the saturated vapor pressure of the Al element of the same condition.展开更多
文摘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<P<Pimpe. A method has been put forward to calculate the pcrit and pimpe of Al evaporation in a Ni-XAI (x=25-50 at. pct) melt. The calculation result shows that the pcrit or pimpe is a second-order function of the molar percentage of Al and the melting temperature.
文摘A new model was established to calculate the real vapor pressure of Al in the molten Ni-xAl （at.pct） （x=25;0） 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.
基金Project(50271020 50395102) supported by the National Natural Science Foundation of China Project(2002AA305209)supported by Hi tech Research and Development Program of China
文摘Based on the program developed to simulate the temperature field for ISM(Induction Skull Melting) process, the effects of power increasing rate and charge mass on the melting throughout time and the energy (consumption) for TiAl alloys were studied. The results show that the melting throughout time decreases (exponentially) with the increasing of the power increasing rate and it linearly increases with the increasing of the charge mass. There is a critical power increasing rate for different charge masses. At this critical power increasing rate, the charge can be molten when the melting power just reaches 300 kW. There exists an optimal power increasing rate, i.e. 1.3 kW/s. At the optimal power increasing rate, the energy consumption for melting the charge is the minimum. The charge mass has noticeable influence on the energy consumed by unit mass and the ratio of effective energy.
文摘A new model was established to calculate the real vapor pressure of the Al element in the molten Ti x Al ( x = 25 ～ 50, mole fraction, %) alloy. The effects of the holding time, chamber pressure, mole fraction of Al and melting temperature on the real vapor pressure of Al element 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 the Al component, the real vapor pressure of Al is equal to the chamber pressure. While when the chamber pressure is larger than the saturated vapor pressure, the real vapor pressure is equal to the saturated vapor pressure of the Al element of the same condition.
