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采用CAF模型对真空自耗电弧熔炼γ-TiAl合金铸锭凝固组织进行了数值模拟,在CAF模型中分别采用高斯分布连续形核模型和扩展KGT模型描述晶粒形核和枝晶尖端生长速率。研究了熔炼速率、界面传热系数和形核参数对铸锭凝固组织的影响。结果表明,增大熔炼速率或者增大最大形核密度,均有利于促进等轴晶形成,抑制柱状晶晶粒长大;增大平均形核过冷度或者增大界面传热系数,均有利于促进柱状晶的形成和晶粒长大;标准方差过冷度对铸锭凝固组织几乎没有影响。
The solidification microstructure of γ-TiAl alloy ingot in vacuum consumable arc melting was numerically simulated by CAF model. In the CAF model, Gaussian distribution continuous nucleation model and extended KGT model were used to describe the grain nucleation and dendrite tip growth rate. The effects of smelting rate, interfacial heat transfer coefficient and nucleation parameters on ingot solidification were investigated. The results show that increasing the melting rate or increasing the maximum nucleation density can promote the formation of equiaxed grains and inhibit the growth of columnar grains; increase the average nucleation undercooling or increase the interfacial heat transfer coefficient Help to promote the formation of columnar crystals and grain growth; standard variance supercooling has almost no effect on the ingot solidification organization.