Effect of Superheat, Heat Transfer Coefficient and Gaussian Distribution Parameters on Solidification Structure of Ag-28Cu-2Ni Alloy
FANG Jiheng1, LIU Xi1, XIE Ming1, HU Jieqiong1, WANG Song1, ZHANG Jiming1, YANG Youcai1, CHEN Yongtai1, WANG Saibei1, LI Zaijiu2
1 Kunming Institute of Precious Metals, Kunming 650106 2 Department of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650093
Abstract: Based on the CAFE method (cellular automaton-finite element coupling model), the three-dimensional microstructure under the water-cooled copper mold casting conditions was simulated with the help of Procast software, the simulation results are in agreement with the experimental results. In addition, the effect of the process parameters (superheat and heat transfer coefficient) and the Gauss distribution parameters (the nucleation undercooling (ΔTv(s),max), the maximum nucleation density (nv(s),max), and the standard deviation of nucleation undercooling (ΔTv(s),σ) on the solidification structure of the alloy was also studied. The simulation results show that with the increase of superheat, the proportion of columnar crystals gradually increases, the grain size of the fine columnar crystals increases, and the CET (columnar to equiaxed transition) transformation position shifts to the interior of the alloy casting. Under the condition of water cooling (h=5 000 W/(m2·K)), the solidification structure of Ag-28Cu-2Ni alloy is almost all columnar crystals, and the grain is coarse. Under the condition of air cooling (h=2 000 W/(m2·K)), the columnar crystal region shrinks, and the equiaxed crystal area occupy the major part. Under the condition of slow cooling (h=10 W/(m2·K)), the solidification structure of the casting is almost entirely equiaxed crystals. Furthermore, the higher the mean undercooling, the larger the columnar dendrite zones, and the larger the maximum nucleation density, the smaller the size of grains. The larger the standard deviation, the more discrete the grain distribution, and the more uniform the grain size distribution.
方继恒, 刘曦, 谢明, 胡洁琼, 王松, 张吉明, 杨有才, 陈永泰, 王塞北, 李再久. 过热度、传热系数以及高斯分布参数对Ag-28Cu-2Ni合金凝固组织的影响[J]. 材料导报, 2019, 33(18): 3077-3084.
FANG Jiheng, LIU Xi, XIE Ming, HU Jieqiong, WANG Song, ZHANG Jiming, YANG Youcai, CHEN Yongtai, WANG Saibei, LI Zaijiu. Effect of Superheat, Heat Transfer Coefficient and Gaussian Distribution Parameters on Solidification Structure of Ag-28Cu-2Ni Alloy. Materials Reports, 2019, 33(18): 3077-3084.
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