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研究了Ni基高温合金Ni-10Cr-15Co-6W-6Mo-4Al-2Ti真空熔炼过程中Mg挥发动力学。结果表明,真空感应熔炼过程中,当炉内Ar压力保持在100—400mmHg时,合金中Mg挥发速率受Mg在液相边界层中扩散及金属熔池/气相界面挥发反应双重控制,而非受控于气相边界层中Mg的扩散。双重控制时Mg的传质系数为10~(-5)—10~(-2)cm·s~(-2)数量级,而气相边界层中Mg的传质系数为140cm·s~(-1)左右。借助于动力学公式、回归方程及特殊的参数转换,建立了一个简单的Mg挥发数学模型,该模型计算结果与实验室及生产条件下试验数据很好地符合,因此,可通过控制熔炼参数,例如向金属熔池加Mg量,Ar压力,挥发温度及时间等来精确地控制最佳Mg含量。
The volatilization kinetics of Mg during the vacuum smelting of Ni-based superalloy Ni-10Cr-15Co-6W-6Mo-4Al-2Ti was studied. The results show that when the Ar pressure in the furnace is kept at 100-400mmHg in the vacuum induction melting process, the rate of Mg volatilization in the alloy is controlled by the diffusion of Mg in the liquid boundary layer and the volatilization reaction at the metal bath / gas phase interface, Controlling the diffusion of Mg in the vapor boundary layer. The mass transfer coefficient of Mg in the dual control is in the order of 10 -5 to 10 -2 cm -2 s -1 while the mass transfer coefficient of Mg in the gas phase boundary layer is 140 cm · s -1 )about. With the aid of kinetic formula, regression equation and special parameter transformation, a simple mathematical model of Mg volatilization was established. The calculation results of this model are in good agreement with the experimental data under laboratory and production conditions. Therefore, by controlling melting parameters, For example, the amount of molten metal bath plus Mg, Ar pressure, volatilization temperature and time to accurately control the optimal Mg content.