摘要
以透明模型合金丁二腈－乙醇系为实验系统，直接观察其单相凝固过程中界面形态的非稳态演化过程，从三个方面：①平胞转变②胞核转变③枝晶一次间距，系统地考察了凝固界面形态选择的时间相关性和历史相关性结果表明：①导出了凝固初始过渡区溶质再分配的一个新公式；②提出了确定平界面稳定性临界条件的可测判据和实验方法；③从实验上和理论上解释了胞枝转变行为；④揭示了枝晶一次间距的历史相关性；⑤发现凝固形态选择的历史相关性的大小与系统离开平衡的程度相关．
In situ observation of non-steady state process of interface pattern formation during unidirectional solidification were performed by using a typical transparent model alloy system------succinonitrile Time-dependent development and history-dependent steady-state selection of two important critical points of interface pattern transition(planar to cellular and cellular to dendritic transition) and one important characteristic scale(primary dendritic spacing)during constrained crystal growth of a single phase alloy were systematically investigated. The main results are as follows f (1) a new equation of initial transient solute redistribution was deduced: (2) a new experimental method was developed to identify the critical condition for interface instability. (3) a new equation for cell-dendrite transition point. which was deduced from a qusi-dynamical analysis of the pattern developing process. agrees excellently with the experimental observation: (4) selection of average primary dendritic spacings is considerably history-dependent; (5) history-dependence of interface pattern selection is related to the degree that the system deviates from equilibrium.
出处
《材料研究学报》
EI
CAS
CSCD
1995年第3期193-207,共15页
Chinese Journal of Materials Research
基金
国家自然科学基金
关键词
界面形态选择
非稳态过程
凝固界面形态
interface pattern selection, cell-dendrite transition, interface morphology stability, primary dendritic spacing
