摘要
We simulate the evolution of hydrogen concentration and gas pore formation as equiaxed dendrites grow during solidification of a hypoeutectic aluminum-silicon(Al-Si)alloy.The applied lattice Boltzmann-cellular automaton-finite difference model incorporates the physical mechanisms of solute and hydrogen partitioning on the solid/liquid interface,as well as the transports of solute and hydrogen.After the quantitative validation by the simulation of capillary intrusion,the model is utilized to investigate the growth of the equiaxed dendrites and hydrogen porosity formation for an Al-(5 wt.%)Si alloy under different solidification conditions.The simulation data reveal that the gas pores favorably nucleate in the corners surrounded by the nearby dendrite arms.Then,the gas pores grow in a competitive mode.With the cooling rate increasing,the competition among different growing gas pores is found to be hindered,which accordingly increases the pore number density in the final solidification microstructure.In the late solidification stage,even though the solid fraction is increasing,the mean concentration of hydrogen in the residue melt tends to be constant,corresponding to a dynamic equilibrium state of hydrogen concentration in liquid.As the cooling rate increases or the initial hydrogen concentration decreases,the temperature of gas pore nucleation,the porosity fraction,and the mean porosity size decrease,whilst the mean hydrogen concentration in liquid increases in the late solidification stage.The simulated data present identical trends with the experimental results reported in literature.
作者
Qingyu Zhang
Dongke Sun
Shunhu Zhang
Hui Wang
Mingfang Zhu
张庆宇;孙东科;章顺虎;王辉;朱鸣芳(Shagang School of Iron and Steel,Soochow University,Suzhou 215137,China;Jiangsu Key Laboratory for Advanced Metallic Materials,School of Materials Science and Engineering,Southeast University,Nanjing 211189,China;Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments,School of Mechanical Engineering,Southeast University,Nanjing 211189,China;State Key Laboratory for Advanced Metals and Materials,University of Science and Technology Beijing,Beijing 100083,China)
基金
Project supported by the National Natural Science Foundation of China(Grant No.51901148)
the Fund of the State Key Laboratory of Solidification Processing(Northwestern Polytechnical University),China(Grant No.SKLSP202006)
the State Key Lab of Advanced Metals and Materials(University of Science and Technology Beijing),China(Grant No.2019-Z15).
