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采用光悬浮区熔定向凝固技术制备了Nb-Mo-Si三元共晶合金,研究了试棒旋转速度和抽拉速度对Nbss-β(Nb,Mo)5Si3共晶组织形态的影响。结果表明籽晶棒的旋转对组织形态有显著影响,而料棒的旋转对组织形态的影响并不明显。当抽拉速度是5mm/h,籽晶棒不旋转时,得到了规则的Nbss-β(Nb,Mo)5Si3片层结构;而当籽晶棒旋转时,试棒中心处为先析出的球状Nbss和规则片层组织,沿径向向外,规则的片层组织逐步转变成不规则的碎块状组织。当籽晶棒不旋转,抽拉速度是1mm/h时,组织为不规则共晶组织,Nbss倾向于连成网状;当抽拉速度是3～5mm/h时,形成典型的规则片层组织;当抽拉速度是10mm/h时,具有片层组织的柱状晶和胞状晶共存。此外,从液/固界面特性及过冷度的角度对组织多样性进行了讨论。
The Nb-Mo-Si ternary eutectic alloy was prepared by the melt-solidification technique in the optical suspension zone. The influence of the rotation speed of the test rod and the withdrawal speed on the morphology of NbSi-β (Nb, Mo) 5Si3 eutectic was studied. The results show that the rotation of the seed crystal rod has a significant effect on the morphology of the tissue, while the rotation of the material rod has no obvious effect on the morphology of the tissue. When the drawing speed is 5mm / h, the seed crystal rod is not rotated, the regular Nbss-β (Nb, Mo) 5Si3 sheet structure is obtained. When the seed crystal is rotated, Nbss and regular lamellar organization, the radial outward, the regular lamellar organization gradually transformed into irregular chunks. When the seed rod is not rotating, the pulling speed is 1mm / h, the organization is irregular eutectic, Nbss tend to even into the network; when the drawing speed is 3 ~ 5mm / h, the formation of a typical rule sheet Organization; when the drawing speed is 10mm / h, the columnar crystals and lamellae with lamellar structure coexist. In addition, tissue diversity is discussed in terms of liquid / solid interface characteristics and degree of undercooling.