Modeling of aluminum-silicon irregular eutectic growth by cellular automaton model

作     者：Rui Chen Qing-yan Xu Bai-cheng Liu 

作者机构：School of Materials Science and Engineering Tsinghua University Key Laboratory of Advanced Materials Processing Technology MOE 

出 版 物：《China Foundry》 (中国铸造（英文版）)

年 卷 期：2016年第13卷第2期

页      面：114-122页

核心收录：

学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 080201[工学-机械制造及其自动化] 

基　　金：financially supported by the National Basic Research Program of China(Grant No.2011CB706801) the National Natural Science Foundation of China(Grant No.51374137,51171089) the National Science and Technology Major Projects(Grant No.2012ZX04012-011,2011ZX04014-052) 

主　　题：Al-Si alloys irregular eutectic growth cellular automaton modification numerical simulation 

摘      要：Due to the extensive application of Al-Si alloys in the automotive and aerospace industries as structural components, an understanding of their microstructural formation, such as dendrite and(Al+Si) eutectic, is of great importance to control the desirable microstructure, so as to modify the performance of castings. Since previous major themes of microstructural simulation are dendrite and regular eutectic growth, few efforts have been paid to simulate the irregular eutectic growth. Therefore, a multiphase cellular automaton(CA) model is developed and applied to simulate the time-dependent Al-Si irregular eutectic growth. Prior to model establishment, related experiments were carried out to investigate the influence of cooling rate and Sr modification on the growth of eutectic Si. This CA model incorporates several aspects, including growth algorithms and nucleation criterion, to achieve the competitive and cooperative growth mechanism for nonfaceted-faceted Al-Si irregular eutectic. The growth kinetics considers thermal undercooling, constitutional undercooling, and curvature undercooling, as well as the anisotropic characteristic of eutectic Si growth. The capturing rule takes into account the effects of modification on the silicon growth *** simulated results indicate that for unmodified alloy, the higher eutectic undercooling results in the higher eutectic growth velocity, and a more refined eutectic microstructure as well as narrower eutectic lamellar spacing. For modified alloy, the eutectic silicon tends to be obvious fibrous morphology and the morphology of eutectic Si is determined by both chemical modifier and cooling rate. The predicted microstructure of Al-7Si alloy under different solidification conditions shows that this proposed model can successfully reproduce both dendrite and eutectic microstructures.