Traveling waves, two-phase fingers, and eutectic colonies in thin-sample directional solidification of a ternary eutectic alloy

被引:65
作者
Akamatsu, S
Faivre, G
机构
[1] Univ Denis Diderot, CNRS UMR 7588, Phys Solides Grp, F-75251 Paris 05, France
[2] Univ Paris 06, CNRS UMR 7588, Phys Solides Grp, F-75251 Paris, France
来源
PHYSICAL REVIEW E | 2000年 / 61卷 / 04期
关键词
D O I
10.1103/PhysRevE.61.3757
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
We present an experimental investigation of the morphological transition of lamellar eutectic growth fronts called "formation of eutectic colonies" by the method of thin-sample directional solidification of a transparent model alloy, CBr4-C2Cl6. This morphological transition is due to the presence in the melt of traces of chemical components other than those of the base binary alloy (impurities). In this study, we use naphthalene as an impurity. The formation of eutectic colonies has generally been viewed as an impurity-driven Mullins-Sekerka instability of the envelope of the lamellar front. This traditional view neglects the strong interaction existing between the Mullins-Sekerka process and the dynamics of the lamellar pattern. This investigation brings to light several original features of the formation of eutectic colonies, in particular, the emission of long-wavelength traveling waves, and the appearance of dendritelike structures called two-phase fingers, which are connected with this interaction. We study the part played by these phenomena in the transition to eutectic colonies as a function of the impurity concentration. Recent theoretical results on the linear stability of ternary lamellar eutectic fronts [Plapp and Karma, Phys. Rev. E 60, 6865 (1999)] shed light on some aspects of the observed phenomena.
引用
收藏
页码:3757 / 3770
页数:14
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