SiC_W/6061Al铝基复合材料激光焊机理

Mechanism of Laser Welding for SiC_w/6061Al Composite

采用脉冲激光焊接方法对SiCW/ 6 0 6 1Al复合材料进行焊接试验。研究了试件表面处理状态、保护气体、激光输出功率、焊接速度、激光脉冲频率等工艺参数对焊接质量的影响规律。试验结果表明 ,激光输出功率和焊接速度对焊缝的显微组织和焊接质量都有较大的影响 ,激光脉冲频率的变化对焊接质量有一定的影响 ,而试件表面的处理状态对焊接质量影响不大。同时发现 ,利用N气代替Ar气也取得了较好的保护效果。利用扫描电镜和透射电镜对焊缝进行显微观察 ,从微观角度分析了焊缝接头强度损失的机理 ,认为焊接时SiC晶须与基体Al发生反应而烧损及生成较脆的界面反应物是造成接头强度下降的重要原因。提出了临界硅活度α[Si]min的概念 ,成功实现了铝基复合材料SiCW/ 6 0 6 1Al的激光焊接。

SiC w/6061Al composite was welded by pulse laser welding successfully.The influence of the parameters such as surface treatment state,laser output power,welding speed,protective atmosphere,and pulse frequency on the welding quality was studied.The results show that laser output power and welding speed are the main factors which affect the microstructure and the property of weld,and change of laser pulse frequency has the definite influence on them.However,surface treatment state has little influence on the properties of joint.At the same time,we obtained good effect by using nitrogen gas instead of argon gas.The microstructure of joint was observed and the strength loss of joint was analyzed by SEM and TEM.The main reason for the decrease of the strength of welded joint is that when laser welding was used,SiC whisker reacted with Al to form brittle Al 4C 3.Therefore,the conception of the critical activity α [Si]min was put forward.