Jiuzhou ZHAO
,
L.Ratke
,
Jun JIA
,
Qingchun LI
材料科学技术（英）
The microstructure development during a cooling period of alloys being immiscible in the liquid state such as Al-Pb or Al-Bi has gained renewed scientific and technical interest during the last decades. Experiments have been performed to investigate the phase transformation kinetics in the liquid miscibility gap and numerical models have been developed to simulate and analyze the solidification process. The recently developed computational modeling techniques can, to some extent, be applied to describe the decomposition, the spatial phase separation and the microstructure evolution during a cooling period of an immiscible alloy through the miscibility gap. This article overviews the researches in this field.
关键词:
Immiscible alloy
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Jiuzhou ZHAO
,
L.Ratke
材料科学技术（英）
A numerical model is presented describing the microstructure evolution of an immiscible alloy under the continuous casting conditions. Calculations are carried out to investigate the microstructure evolution in a vertical strip cast sample of Al+5 wt pct Pb alloy. The numerical results show that there exists a peak value for the supersaturation in front of the solid/liquid interface, and the minority phase droplets are nucleated in a region around this peak. Under strip casting conditions the Marangoni migration dominates the motion of droplets. This leads to an accumulation of the minority phase droplets in front of the solid/liquid interface.
关键词:
Immiscible alloy
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null
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Jiuzhou ZHAO
材料科学技术（英）
Modeling and simulation have been carried out for Al-Pb alloys to investigate the Brownian coagulation effect on the microstructure development in a gas-atomized drop during the liquid-liquid decomposition. The results indicate that Brownian coagulation has a weak effect on the nucleation and a relatively strong effect on coarsening the minority phase droplets. The influence of Brownian coagulation on the liquid-liquid decomposition decreases with the increase in the diameter (or the decrease in the cooling rate) of the atomized drop.
关键词:
Immiscible alloy
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Jiuzhou ZHAO
,
Dongming LIU
,
Hengqiang YE
材料科学技术（英）
In order to understand the solidification process of an atomized droplet and predict the fraction solidification of droplets with flight distance during spray forming, a numerical model based on the population dynamics approach is developed to describe the microstructure evolution under the common action of the nucleation and growth of grains. The model is coupled with droplets heat transfer controlling equations and solved for Al-4.5~wt~pct Cu alloy. It is demonstrated that the numerical results describe the solidification process well.
关键词:
Rapid solidification
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