中国物理B ›› 2006, Vol. 15 ›› Issue (7): 1631-1637.doi: 10.1088/1009-1963/15/7/042
苏云鹏, 林鑫, 王猛, 薛蕾, 黄卫东
Su Yun-Peng (苏云鹏), Lin Xin (林鑫), Wang Meng (王猛), Xue Lei (薛蕾), Huang Wei-Dong (黄卫东)
摘要: This paper reports on laser surface remelting experiments performed on a Zn--2wt.%}Cu hypoperitectic alloy by employing a 5kW CW CO2 laser at scanning velocities between 6 and 1207mm/s. The growth velocities of the microstructures in the laser molten pool were accurately measured. The planar interface structure caused by the high velocity absolute stability was achieved at a growth velocity of 210~mm/s. An implicit expression of the critical solidification velocity for the cellular--planar transition was carried out by nonlinear stability analyses of the planar interface. The results showed a better agreement with the measured critical velocity than that predicted by M--S theory. Cell-free structures were observed throughout the whole molten pool at a scanning velocity of 652~mm/s and the calculated minimum temperature gradient in this molten pool was very close to the critical temperature gradient for high gradient absolute stability (HGAS) of the \eta phase. This indicates that HGAS was successfully achieved in the present experiments.
中图分类号: (Solidification)