Zhongfan LIU
,
Xuede YUAN
材料科学技术（英文）
Laser interference induced crystallization of amorphous silicon (a-Si) on the glass substrate was performed using a Q-switched Nd:YAG (yttrium aluminum garnet) laser. White light interferometer (WLI) and atomic force microscope (AFM) were used to characterize the morphology of the structured films, while X-ray diffraction (XRD), combined with the AFM, was used to analyse the crystalline structure of the film. The experimental results show that the laser energy density above a certain threshold, in the range of 400–500 mJ/cm2, triggers the patterned crystallizations which take the form similar to the laser intensity distribution. For the patterned crystallization under multipulse exposure, a definite polycrystalline structure with individual phases was observed by XRD. The difference in feature form, e.g., deepened craters or heightened lines, is related to the laser energy density relative to the threshold of evaporation of the material.
关键词:
pulsed laser
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null
,
null
,
null
任维彬
,
董世运
,
徐滨士
,
任君华
,
郑显柱
,
童继凤
材料工程
doi:10.11868/j.issn.1001-4381.2015.001131
采用非接触式红外高温测试仪对连续/脉冲激光成形两种模式下激光再制造FeCrNiCu合金成形层温度场进行分析,获取了熔池及热影响区温度场分布的一般规律,验证了脉冲激光工艺在控制热输入和成形形变以及降低熔池及热影响区温度方面的工艺优越性.结果表明:脉冲激光成形热影响区峰值温度为730.4～810.5℃,熔池峰值温度为998.7～1383.4℃,明显低于相同工艺下连续输出模式;脉冲激光成形层具有更快的升温及降温速率,利于形成细晶组织和获得良好的力学性能;实际成形实验也进一步验证脉冲激光工艺具有更小的热影响区范围.
关键词:
FeCrNiCu合金
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温度场
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激光再制造
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脉冲激光
