Phase field simulation of monotectic transformation for liquid Ni-Cu-Pb alloys  

作　　者：LUO BingChi WANG HaiPeng WEI BingBo 

机构地区：[1]Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, China

出　　处：《Chinese Science Bulletin》2009年第2期183-188,共6页

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 50121101, 50395105)

摘　　要：Based on the subregular solution model, the liquid phase separation of ternary (NixCu100-x)50Pb50 monotectic alloys is simulated by the phase field method. It is found that if the surface segregation potential is not incorporated, the dynamic morphologies of alloy melt show a transition from disperse microstructure into bicontinuous microstructure with the increase of fluidity parameter. When the surface segregation potential is coupled, Pb-rich phase migrates preferentially to the surface of the liquid alloy, and the Ni-rich phase depends on the Pb-rich phase to nucleate. With the extension of the phase separation time, the surface layer is formed through coagulation and growth, and its thickness gradually increases. The Ni-rich phase migrates to the central part, and finally a two-layer core-shell microstructure is produced. The concentration in the surface layer fluctuates more conspicuously than that inside the bulk phase, which subsequently transfers from the surface to the interior by a wave. The fluid field near the liquid-liquid interface is strong at the beginning of phase separation, and reduces later on. The surface segregation is essential to the formation of the surface layer, concentration profile variation, fluid field distribution and phase separation morphology.Based on the subregular solution model, the liquid phase separation of ternary （NixCU100-x）50Pb50 monotectic alloys is simulated by the phase field method. It is found that if the surface segregation potential is not incorporated, the dynamic morphologies of alloy melt show a transition from disperse microstructure into bicontinuous microstructure with the increase of fluidity parameter. When the surface segregation potential is coupled, Pb-rich phase migrates preferentially to the surface of the liquid alloy, and the Ni-rich phase depends on the Pb-rich phase to nucleate. With the extension of the phase separation time, the surface layer is formed through coagulation and growth, and its thickness gradually increases. The Ni-rich phase migrates to the central part, and finally a two-layer core-shell micro- structure is produced. The concentration in the surface layer fluctuates more conspicuously than that inside the bulk phase, which subsequently transfers from the surface to the interior by a wave. The fluid field near the liquid-liquid interface is strong at the beginning of phase separation, and reduces later on. The surface segregation is essential to the formation of the surface layer, concentration profile variation, fluid field distribution and phase separation morphology.

关 键 词：Ni-Cu-Pb合金 偏晶合金 合金微结构 微观相场法 

分 类 号：TG13[一般工业技术—材料科学与工程]