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非均匀温度场下枝晶生长状态
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1.北京科技大学;2.中广核研究院有限公司

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国家自然科学基金(批准号:51375041)


dendrite growth state under non-uniform temperature fieldQin Qin1,2, Ye Chen-Long1, Xie Lu1, Gao Xin-Xin3, Wang Tian1
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国家自然科学基金(批准号:51375041)

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    摘要:

    为了掌握非均匀温度场下微观组织的演变规律,本文采用改进的元胞自动机模型,在完成算法验证的基础上,对比微观组织在均匀温度场和非均匀温度场下组织演变的异同,并系统研究微观组织在非均匀温度场中的枝晶形貌、尖端生长速率和域内溶质分布以及多晶组织的演变规律。研究结果表明:该模型仿真结果与CA-FD模型结果误差范围在1.4%以内;枝晶凝固末端尖端速率在温度均匀场内趋于稳定,而在非均匀场内表现为持续上升;固相溶质浓度在非均匀场内随着枝晶臂的延展而增大,在均匀场内则保持不变。对于非均匀温度场内单枝晶生长,冷速达到10K/s时,枝晶臂的长度达到1030μm,较均匀场增加49.3%,当冷速达到30K/s时,枝晶臂长度达到1460μm,同比增加了111.6%;冷速的加强使枝晶内部固相溶质浓度增加,出现更多侧向枝晶臂,使固/液界面区域溶质出现波动,呈现不规则分布;多晶组织在非均匀温度场内平均溶质浓度随冷速的增大而上升,且域内合金在凝固结束后固相分数比例随冷速的增加由45%增加到65%,同时观察到域内溶质富集,多次枝晶臂的产生和枝晶臂粗化等现象。

    Abstract:

    The mechanical properties of metals are closely related to the microstructure. As the most common solidified microstructure, dendrite has a great influence on the microstructure, and the change of temperature has a significant influence on the microstructure. Domestic and foreign scholar have carried out a lot of studies on the relationship between dendrite growth state and the properties of alloys, however, the study of microstructure growth in uniform temperature field usually ignores the effect of temperature on dendrite growth, which has certain limitations. Therefore, an improved cellular automata model was used to study the effect of temperature variation on dendrite growth in a non-uniform temperature field. The dendrite morphology, dendrite tip growth rate and solute distribution in melt were compared and analyzed under non-uniform temperature field and uniform temperature field. The results show that the dendrite morphology and solute distribution in melt are significantly changed with the change of temperature during the growth process of single dendrite. When the initial undercooling degree is 10K in the undercooled melt, the dendritic arm length of the solidification terminal reaches 1030μm at a cooling rate of 10K/s, which is increased by 49.3% compared with the dendritic arm length of uniform temperature field under the same conditions. When the cooling rate reaches 30K/s, the length of dendrite arm reaches 1460μm, which increases by 111.6%. As the cooling rate increases, the concentration of solid solute in the dendrite increases, but the solute fluctuated at the solid-liquid interface, which results in the non-conservation of solute concentration at the solid-liquid interface and irregular distribution, and more lateral dendrite arms appear. For the growth of multi-dendrite, the solid fraction of the alloy reaches 45% at the cooling rate of 10K/s, which is 15.9% higher than that at isothermal condition. When the cooling rate is up to 30K/s, the solidification area of the alloy accounts for 65%, an increase of 35.9% compared with that in the isothermal state. At the same time, several dendrite arms and the coarsening of dendrite arms are observed in the model domain.

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秦勤,叶陈龙,高鑫鑫,谢璐,王田.非均匀温度场下枝晶生长状态[J].稀有金属材料与工程,2022,51(10):3707~3715.[Qin Qin, Ye Cheng Long, Gao Xin Xin, Xie Lu, Wang Tian. dendrite growth state under non-uniform temperature fieldQin Qin1,2, Ye Chen-Long1, Xie Lu1, Gao Xin-Xin3, Wang Tian1[J]. Rare Metal Materials and Engineering,2022,51(10):3707~3715.]
DOI:10.12442/j. issn.1002-185X.20210798

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  • 收稿日期:2021-09-08
  • 最后修改日期:2022-02-04
  • 录用日期:2022-02-28
  • 在线发布日期: 2022-11-01
  • 出版日期: 2022-10-28