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采用B_2O_3玻璃和纯循环过热净化相结合的方法去除液态金属中的异质晶核,使液态Ni-7.3％Si-2.2％B合金获得了330K的过冷度。对比分析了该合金在低温基板上的快淬薄片与大体积深过冷试样的微观组织。借助计算机和红外测温系统,快速采集了熔体的再辉过程。数据处理发现,在深过冷液态金属的整个再辉区间,温度的上升速率呈瞬态变化特征,再辉时间随初始过冷度的提高而减小。最后,由再辉曲线确定出深过冷液态金属再辉过程中的固相分数与时间以及凝固速度与瞬时过冷度的关系。
The heterogeneous crystal nucleus in liquid metal was removed by the combination of B 2 O 3 glass and pure cycle overheat purification, and the subcooling degree of 330K was obtained for liquid Ni-7.3% Si-2.2% B alloy. The microstructure of rapidly quenched flake and large deep undercooled sample of the alloy at low temperature was analyzed. With the help of computer and infrared temperature measurement system, the process of reflowing the melt is quickly collected. The data processing shows that the rising rate of temperature shows a transient change throughout the reflow interval of the supercooled liquid metal, and the reflow time decreases with the increase of the initial undercooling. Finally, the relationship between solid fraction and time, solidification rate and instantaneous undercooling in deep sub-cooled liquid metal reflow process is determined by the refit curve.