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arXiv 2303.09137cond-mat.mtrl-sci
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增材制造条件下固液界面的形态稳定性

Morphological stability of solid-liquid interfaces under additive manufacturing conditions

D. Tourret, J. Klemm-Toole, A. Eres Castellanos, B. Rodgers, G. Becker, A. Saville, B. Ellyson, C. Johnson, B. Milligan, J. Copley, R. Ochoa, A. Polonsky, K. Pu… 展开作者

D. Tourret, J. Klemm-Toole, A. Eres Castellanos, B. Rodgers, G. Becker, A. Saville, B. Ellyson, C. Johnson, B. Milligan, J. Copley, R. Ochoa, A. Polonsky, K. Pusch, M. P. Haines, K. Fezzaa, T. Sun, K. Clarke, S. Babu, T. Pollock, A. Karma, A. Clarke

摘要:

了解与增材制造(AM)相关的速度下的快速凝固行为对于控制微观结构选择至关重要。虽然原位可视化凝固动力学现在是可能的,系统的研究AM条件下的微观结构的结果相比,凝固理论仍然缺乏。在这里,我们测量固体-液体界面速度的Ni-Mo-Al合金单晶AM条件下与同步辐射X射线成像,表征的微观结构,并显示与经典理论的差异,关于平面固液界面的绝对稳定的起始速度。实验观察表明,细胞/树枝状微观结构可以持续在速度大于预期的绝对稳定性极限,带状结构的形成理论上应该出现。我们表明,理论和实验观察可以调和适当占溶质捕集和动力学过冷的速度依赖的合金的固相线和液相线温度的影响。进一步的理论发展和关键的热物理参数的准确评估-如液体扩散系数,固-液界面过剩自由能,和动力学系数-仍然需要定量研究这种差异,并铺平道路的预测和控制的微观结构选择快速凝固条件下。

英文摘要:

Understanding rapid solidification behavior at velocities relevant to additive manufacturing (AM) is critical to controlling microstructure selection. Although in-situ visualization of solidification dynamics is now possible, systematic studies under AM conditions with microstructural outcomes compared to solidification theory remain lacking. Here we measure solid-liquid interface velocities of Ni-Mo-Al alloy single crystals under AM conditions with synchrotron X-ray imaging, characterize the microstructures, and show discrepancies with classical theories regarding the onset velocity for absolute stability of a planar solid-liquid interface. Experimental observations reveal cellular/dendritic microstructures can persist at velocities larger than the expected absolute stability limit, where banded structure formation should theoretically appear. We show that theory and experimental observations can be reconciled by properly accounting for the effect of solute trapping and kinetic undercooling on the velocity-dependent solidus and liquidus temperatures of the alloy. Further theoretical developments and accurate assessments of key thermophysical parameters - like liquid diffusivities, solid-liquid interface excess free energies, and kinetic coefficients - remain needed to quantitatively investigate such discrepancies and pave the way for the prediction and control of microstructure selection under rapid solidification conditions.

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