低速凝固与亚快速凝固界面非稳态演化规律实验研究  

Non-Steady State Evolution of Interfacial Morphology in Normal and Sub-Rapid Directional Solidification

作　　者：王祖锦[1] 傅恒志[1] 

机构地区：[1]西北工业大学

出　　处：《西北工业大学学报》1995年第2期320-322,共3页Journal of Northwestern Polytechnical University

摘　　要：低速凝固与亚快速凝固界面非稳态演化规律实验研究王祖锦，傅恒志凝固过程界面达到稳态之前，界面形态的演化是时间相关的非稳态过程，在不同的凝固条件下，这种非稳态过程表现出不同的演化规律．人们对低速凝固界面形态的非稳态演化规律已有不少实验研知卜斗但对于亚快速...Interfacial morphology undergoes a non-steady state evolution process before steady state. This process shows different features under different solidification conditions. The development of interfacial morphology of normal solidification (low growth rate) has been well studied by many researchers[1-3]. But up to now, no experimental research report on the morphological evolution in sub-rapid solidification has been found in the open literature.In present paper, the directional solidification experiments have been carried out in a transparant carbon-tetrabromide system in-situ for studying the non-steady evolution of interfacial morphology in a wide range of growth rate. Fig 1 (a～d) show the non-steady evolution characteristics of primary spacing λ1 and tip radius R of the typical cell (a) and dcndrite (c) array at low growth rate and cell (b)and dcndritc (d) array at high groWth rate respectively. Symbol E in Fig.1 represents the model of elimination through competition and symbol S represents the model of tip splitting. Fig.2 demonstrates the dynamic evolution morphologics corresponding to Fig.1. The results show that: (1) at low growth rate, the spacing of normal cellular array is adjusted and dominated altCrnatcly by models E and S and both the cell spacing and tip radius appear to vary more or less irregularly (Fig.1 a); (2) in sub-rapid solidification, the adjustment is dominated by model S only over the whole of evolution process, and λ1 decreases monotonically with time (Fig. 1b); (3) at low growth rate, the evolving character of dendrite array is always adjUsted by model E over the whole process (Fig.Zc). which leads to monotonic ir-se of bland monotonic dccrcasc of R (Fig.lc); and (4) in sub-rapid solidification,when is higher than gs, the dendrite evolution is dominated by model S and violent tip-splitting causes a sharp decrease in λ1(Fig. 1d).The results show that the evolution features of sub-rapid solidification are quite different from those of normal solidification. The increase of primary

关 键 词：亚快速凝固 非稳态演化 金属 凝固 界面 

分 类 号：TG111.4[金属学及工艺—物理冶金]