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摘要: 本文采用典型的透明模型合金丁二腈-1.1wt%乙醇进行定向凝固实验,对从平界面失去稳定性到建立起新的稳定的界面形态之间时间相关的形态演化过程进行了详细的直接观察研究。发现:1)平界面失稳初始扰动波长在Mullins-Sekerka(缩写为MS)稳定性理论所预言的波长范围内,但与理论预言的振幅发展最快的波长不一致;2)平界面失稳初期,扰动振幅发展速率确实是振幅的线性函数,但在具体数值上实测值比理论值小得多;3)胞晶和枝晶形态演化过程具有不同的特征,导致这种差别的主要原因是稳态一次间距与初始扰动波长之间相对尺
Abstract: Time-dependent development of interface morphology from initial perturbation of a planar interface to a steady periodic array of cells or dendrites was directly observed during directional solidification brocess of a transparent model alloy, succinonitrile -1.1 wt% ethanol. The following results are obtained: 1) The measured wavelength of initial perturbation of planar interface instability is within the expected wavelength range by the MS theory, but not the same as the expected wavelength with the fastest amplitude developing speed. 2) During the initial stage of a planar interface instability, the developing speed of perturbation amplitude is indeed a linear function of the amplitude, but the measured value of the amplitude developing rate is much smaller than the theoretical value. 3) The features of morphology development of cells and dendrites are different from each other, and the main cause leading to the different developing behaviour is that the relative scale of the steady primary spacing and the initial perturbation wavelength is different in the two cases.