(西北工業(yè)大學(xué) 理學(xué)院 空間應(yīng)用物理與化學(xué)教育部重點(diǎn)實(shí)驗(yàn)室，西安 710129)
摘 要: 材料的微觀組織結(jié)構(gòu)對(duì)材料的性能具有決定性的作用，而凝固過程中橫向限制的存在則會(huì)直接影響晶體微觀結(jié)構(gòu)的演化過程。利用非等溫的相場(chǎng)模型，以純金屬Ni為研究對(duì)象，模擬了其在橫向擋板限制下的微觀組織演化過程，研究不同形狀橫向擋板對(duì)不同初始枝晶間距枝晶演化過程的影響，討論擋板形狀對(duì)枝晶間距的調(diào)整作用。結(jié)果表明：橫向限制的存在會(huì)明顯改變晶體的生長(zhǎng)和發(fā)育過程，且不同形狀橫向擋板的限制均會(huì)對(duì)枝晶間距產(chǎn)生顯著的影響：上三角形擋板對(duì)枝晶間距的改變最明顯；下三角形及矩形的橫向限制對(duì)枝晶間距具有一定的控制作用，即對(duì)于不同初始間距枝晶繞過這兩類擋板后具有基本相同的重新發(fā)育模式，枝晶間距只與擋板尺寸有關(guān)，與初始枝晶間距關(guān)系不大；不同尺寸梯形擋板對(duì)于枝晶間距具有完全不同的調(diào)整作用，通過調(diào)整梯形擋板尺寸比例可以有效實(shí)現(xiàn)改變枝晶間距的作用。因此，在凝固過程中引入不同性質(zhì)的橫向限制可以有效地實(shí)現(xiàn)枝晶間距調(diào)整。
關(guān)鍵字: 相場(chǎng)方法；橫向擋板；枝晶間距
（Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education,
School of Science, Northwestern Polytechnical University, Xi’an 710129, China）
Abstract:The mechanical properties of materials are strongly dependent upon their microstructures, and the lateral constrains in presence of melt have a significantly effect on the microstructure evolution. A non-isothermal phase-field model for pure metal was implemented to simulate the microstructure evolution in the presence of lateral constrains of different shapes during the solidification of pure Ni, in order to study the effect of lateral constrains on the dendritic spacing changes caused by these lateral constrains. The results indicate that lateral constrains have a direct influence on the dendrite development, and the lateral constrains of different shapes can lead to different influences on the dendrite arm spacing changes. The constrains of triangle with sharp corner at the bottom has the most significant influence on the dendrite spacing changes, and rectangle and triangular constrains with its sharp corner above show a controlling effect on the dendrite arm spacing, that is, the dendrite growth of different primary arm spacings has the same developing manner with these two kinds of lateral constrains, the new developing dendrite arm spacing is determined by the shape of constrains, and has less relationship with its primary arm spacing. When the lateral constrain of trapezoid is introduced, the dendrite arm spacing can be determined by changing the size of the hemline of constrains. Therefore, the lateral constrains in the solidification process can significantly change the dendrite arm spacing.
Key words: phase-field method; lateral constrains; dendrite arm spacing
