中国物理B ›› 2006, Vol. 15 ›› Issue (7): 1631-1637.doi: 10.1088/1009-1963/15/7/042

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Absolute stability of the solidification interface in a laser resolidified Zn--2wt.%Cu hypoperitectic alloy

苏云鹏, 林鑫, 王猛, 薛蕾, 黄卫东   

  1. State Key Laboratory of Solidification Processing,Northwestern Polytechnical University, Xi'an 710072, China
  • 收稿日期:2005-10-11 修回日期:2005-12-07 出版日期:2006-07-20 发布日期:2006-07-20

Absolute stability of the solidification interface in a laser resolidified Zn--2wt.%Cu hypoperitectic alloy

Su Yun-Peng (苏云鹏), Lin Xin (林鑫), Wang Meng (王猛), Xue Lei (薛蕾), Huang Wei-Dong (黄卫东)   

  1. State Key Laboratory of Solidification Processing,Northwestern Polytechnical University, Xi'an 710072, China
  • Received:2005-10-11 Revised:2005-12-07 Online:2006-07-20 Published:2006-07-20

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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.

关键词: rapid solidification, absolute stability, laser surface resolidification, Zn--Cu peritectic alloy

Abstract: 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.

Key words: rapid solidification, absolute stability, laser surface resolidification, Zn--Cu peritectic alloy

中图分类号:  (Solidification)

  • 81.30.Fb
42.62.-b (Laser applications) 68.08.-p (Liquid-solid interfaces) 81.30.Bx (Phase diagrams of metals, alloys, and oxides)