Abstract
Liquid concentration distribution is seriously affected by an abruptly changing pulling velocity under directional solidification. Theoretical and numerical investigations indicate that at the pulling velocity jumping from V 0 to V, the solidification system does not achieve the pulling velocity V immediately, and it goes through a non-steady-state transition zone. As the pulling velocity abruptly increases (V/V 0 > 1), interface liquid concentration firstly increases to the maximum and then decreases to the steady-state value. The magnitude of interface liquid concentration at the beginning increases with V/V 0, the initial pulling velocity V 0 and the temperature gradient G L in the liquid. At the same time, solute diffusion length reduces with V/V 0 and G L. In contrast, the minimum of interface liquid concentration falls with V/V 0 at the pulling velocity decreasing abruptly. As the interface liquid concentration enriched at V/V 0 > 1 is more than the value required for the planar interface to keep stable, the solid/liquid interface may become unstable. The analytical results are in agreement with the numerical calculation results of Al-2%Cu alloy.
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Supported by the National Natural Science Foundation of China (Grant Nos. 50401014, 50395102) and DPOP Project in NWPU
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Li, S., Fu, H. Liquid concentration distribution and planar interface instability at an abruptly changing pulling velocity in directional solidification. SCI CHINA SER E 50, 118–126 (2007). https://doi.org/10.1007/s11431-007-0010-8
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DOI: https://doi.org/10.1007/s11431-007-0010-8