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在内径为1 mm的细管中进行了Fe-4.2Ni亚包晶合金扩散条件下的定向凝固实验.在15μm/s抽拉速率下得到了树状组织、共生组织以及δ/γ两相分离生长的凝固组织,组织演化规律为:δ单相→δ/γ两相树状组织→γ+两相共生组织→δ/γ两相分离并列生长组织;抽拉速率为35μm/s时,获得了以γ岛状为主的凝固组织,组织演化规律为:δ单相→δ/γ两相树状组织→γ-岛状组织+共生组织→δ+γ-岛状组织.实验发现,提高抽拉速率使凝固初始阶段的两相生长竞争加剧,并导致凝固过程中的相选择和全程组织演化规律发生改变.
Directional solidification experiments were carried out in a thin tube with an inner diameter of 1 mm under the diffusion of Fe-4.2Ni sub-peritectic alloy. Dendritic structure, symbiotic structure and δ / γ phase separation were obtained at a pull rate of 15μm / s The solidified tissue grew in the following order: δ single phase → δ / γ two-phase dendritic structure → γ + two-phase symbiosis → δ / γ two-phase separation and parallel growth; when the drawing speed was 35μm / s, In order to γ-island-shaped solidification organization, the evolution of microstructure: δ single phase → δ / γ two-phase dendritic tissue → γ-island tissue + symbiotic tissue → δ + γ- island tissue .Experiment found that increasing The pull-out rate aggravates the competition between the two phases in the initial stage of solidification and leads to the change of phase selection and the whole evolution of microstructure in the solidification process.