Nucleation barrier height in undercooled metallic melts

查看全文 作　　者：Gang [1]WANG;Dechang [1]ZENG;Zhongwu [1]LIU 机构地区：[1]School of Materials Science and Engineering,South China University of Technology,Guangzhou 510640,China 出　　处：《Acta Metallurgica Sinica(English Letters)》索引2012年第25卷第4期,共9页 基　　金：supported by the National Natural Science Foundation of China(Grant No. 51101059);China Postdoctoral Science Foundation (Grant No.20110490874) 摘　　要：The phase-field model of a liquid-to-solid transition was constructed where the model parameters were linked quantitatively to the interfacial properties,and the variation of nucleation barrier height in undercooled metallic melts with respect to undercooling was studied respectively based on two kinds of forms of local free energy density.The calculation results show that,with the increase of undercooling,the critical nucleus does not show bulk properties,and the nucleation barrier height decreases gradually and deviates more and more from that predicted by the classical nucleation theory in both cases.The physical spinodal occurs for a specific form of the local free energy density,where the nucleation barrier height vanishes when the undercooling reaches a critical value and the reduced nucleation barrier height can be expressed by a function of the ratio of undercooling to critical undercooling. 关 键 词：临界过冷度 势垒高度 金属熔体 形核 能量密度 界面性能 模型参数 相场模型