Hua HOU
,
Dong-Ying Ju
,
Yuhong ZHAO
,
Jun CHENG
材料科学技术（英文）
Two-dimensional numerical simulation for the dendrite growth of binary alloy during solidification is carried out by a phase field method. In the model equations, phase field, temperature and solute redistribution are all involved. The equations are solved using the finite difference method (FDM) with two different space steps of phase field and temperature field. In calculation, the thermal noise is introduced to generate the side branches; the dependence of dendrite growth on the space step was also investigated. It is shown that thermal noise can trigger the growth of side-branches, however it has no influence on the stable behavior of the dendrite tip; the feature of dendrite growth is reasonable with δ Δx≤0.6W0, Δx is the space step and W0 is the thickness of interface.
关键词:
Phase field
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Gang WANG
,
Dechang ZENG
,
Zhongwu LIU
金属学报(英文版)
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:
Nucleation
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